Further advice on tipping: I wouldn’t completely agree with SciFiSam here: I’d tip waiters, but never cabbies (unless it’s just your change and pittance at that), and certainly not bar staff, except for the ‘one for yourself’ rule.
My friend got the adapter whatsit for her hair dryer from her local Wal-mart, before we went to Ireland.
Because you just never know, keep your passport with you at all times and a paper copy of it in your luggage. I slept with mine under my pillow every night - but that’s just me in a different bed and breakfast every night. Know where your American embassies are while traveling in the United Kingdom, write the addresses and telephone numbers down on paper and keep that in your wallet.
Find out if it’s really really necessary to take American Express traveller’s checks rather than American greenbacks to spend. I thought I had to. As it turned out, Ireland would have been more than happy to take my greenbacks. Silly me. In 2002, for every 100 dollars worth of TC, it cost me ten bucks to convert them inside ye merry olde Bank of Ireland. :rolleyes:
Another reminder to look right before stepping off. It took a little while and a couple of sharp-eyed Irish folks to keep this dumb American from becoming a dead American as well. You’ll adapt. In fact you’ll be amazed at how fast you do.
Surprisingly, I had less trouble remembering which side of the road to drive on. Still, I would’ve loved to have had a sign ala ‘The Partridge Family’ in my rear window. Instead of ‘Careful: Nervous Mother Driving,’ mine would have been, ‘Nervous **American **Driving.’ 
Don’t bother with traveller’s cheques, just get Sterling from an ATM - usually the exchange rate is pretty good, and certainly better than any Bureau de Change. If you must exchange physical currency when you are here, use a Post Office.
ETA make sure your debit card or whatever you are using has a 4-digit pin.
Really? I’ve never heard of anyone not tipping the cabby, unless he’s done something egregious (like the minicab driver who drove me from Crystal Palace to Peckham via Catford and only ended up getting me home because I insisted on getting into the front and directing him using his A-Z). Always waiters. I don’t think I’ve ever tipped bar staff, though in pubs where I’ve been a regular I would invite them to have “one for yourself”.
I had no problems there, but that’s because I have relatives there and speak the language. 
In a lot of places in central London they have words printed on the sidewalk: LOOK LEFT or LOOK RIGHT. This is partly because the streets are narrow, often one way, and come in at weird angles, so you don’t know what to expect anyways. (BTW, if Brits say, “pavement”, they mean “sidewalk”. “Pavement” does not mean “the hard substance covering the road”.)
There is no grid system to the street layout in most places, which can be a lot more disorienting than it seems at first. It’s surprising how much we subconsciously rely on a grid layout if we’ve grown up with one. I have a theory that the streets in London were laid out by drunken farm animals fleeing the Vikings, but that’s just me. There are some landmarks that are useful for orientation, but again, because the streets are often narrow, they may not be visible.
Credit cards: if you are using US-style “swipe-and-sign” cards with a magnetic stripe on the back, be aware that the UK, like many places around the world, uses “chip-and-pin” cards. These have an electronic chip, whose contacts are visible as a square on the front of the card. You insert a chip-and-PIN card into the reader, leave it there, and enter a PIN on the keypad. There is no need to sign.
Your “swipe-and-sign” card should work where there is an attendant or cashier, but shop personnel may not be used to swiping a card and getting a receipt to present for a signature, and it may take some extra time. High-tourist places should be used to it though.
I have heard that swipe-and-sign cards may not work at all in unattended facilities like tollbooths and ticket machines.
Perhaps it’s a regional taste? I’ve never done it, and an American I had with me once told me she tried to tip a London cabbie who looked kind of bemused and embarassed when she gave him a five pound note as tip.
http://www.lagunatandoori.co.uk/
This place is supposed to be one of the best curry houses in Nottingham (Though the menu looks a bit meh to me, I’ve had it recommended before) You do like Curry don’t you? 
Otherwise, the UK is very similar to the US and the differences are rather small but sometimes suprising, I don’t really think there’s much worth telling you about in all honesty. The small things are the most fun to find for yourself.
Two hours? Maybe, although I would have thought more. In any case, your hosts are likely to think of that as being a pretty long journey, not a short trip.
The “one for yourself” rule is exceptional though: I never heard anyone say this at all, ever, the entire time I lived in the UK.
I’m in the UK and I tip taxi drivers if they carry my stuff more than a few yards.
ETA I generally tip then ask politely if they’ll take my bags of shopping to the back door.
I’ve never been in a cab in the UK when anyone’s done more than say ‘keep the change’, and frequently no-one’s bothered with that. I don’t tend to hire them meself, just as part of a group.
Don’t try and use American Express- one of the most commonly used systems will not accept it. Visa and Mastercard are what we use- at least pretty much anywhere not in a remote country shack; I can’t remember when I last went somewhere that didn’t accept them, though they may have a minimum purchase of £5 or even £10 to use in smaller places.
We only fully changed to chip-and-pin about 5 years ago, and our cards still have the magnetic strip (maybe as a back-up) so even in obscure places, it won’t be too odd if you have to sign. Working as a shop assistant, we got the odd person in using it (for anyone British and curious- if you’re disabled, you can apply to sign rather than use the pin system- presumably so a carer doesn’t nick the card and clear you out).
Umm… Other random stuff- if you’re planning to go to Scotland, bear in mind that though the Scots will cheerfully accept English money, English shops often won’t accept Scottish notes, (simply because they rarely see them- they are legal tender, and you can exchange them at a bank or post office) something tourists sometimes fall foul of.
Slightly obscure, but don’t expect a big dramatic forest as Sherwood Forest- the old word forest doesn’t mean ‘woodland’, it’s just a name for historic wild land/hunting areas. I met a few very disappointed Americans in the New Forest a while ago. It’s largely moorland. 
Oh, and bring a waterproof
Seconded, there is some very pretty countryside around Nottingham. If the weather’s up to it see if you can’t find as nice country pub and sit in the beer garden.
England most definitely will not.
Echoing what’s been said, I found the best exchange rates at ATMs (“cash points” I believe). That is including just using a credit card directly. The trouble with an ATM is that you have to predict how much you’ll need. I never encountered one that charged a fee, so it wasn’t a big deal to only take out enough for a day or two. I can still remember the mad dashes to the cash point in Gatwick to get money for the coach leaving in 5 minutes.
And speaking of money, expect that everything will cost about the same number as it does in the US, just the currency changes. For example, a breakfast and coffee might be $12 at a US cafe, so it will cost about £12 ($18!) in a British cafe. Tax is usually included in the menu price.
If you a have world phone on AT&T or T-Mobile (the only two US carriers who use the same GSM phone system as used in the UK) then your phone should work in the UK. It will be expensive! AT&T used to offer an international plan that made it about $1/minute just for asking, but the regular price was $2+/minute. There were other international plans which had a monthly fee, but made the roaming cost cheaper.
The hidden gotcha is voicemail. This was the case several years ago, and probably still is. If your phone is on, and you let a call go to voicemail, that counts as your phone answering, and then forwarding the call to the US, so you get hit with double charges for as long as the person is leaving the message. If the phone is off, then there is no charge if a call goes to voicemail. Every time I’d go overseas I’d call AT&T and have them turn off my voicemail, so I could keep my phone on for text messages, but not have to worry about getting a big roaming bill.
Even with the cost of international texts, $.45 or so, they are still a great of saying “I’m done at the museum and will be getting a pint in Eagle & Child” to your local host. If you have a smart phone, don’t even think of using roaming data. That will be incredibly expensive. As long as you can connect to wifi you should be good with your smarthphone, though.
It’s extraordinarily common. I say it, and I hear it all the time.
If your bank participates in PLUS/CIRRUS/MAESTRO - if you can normally use an ATM that doesn’t belong to your own bank – you should be able to use your ATM card in England to draw pounds directly from your own bank account. However, the machines don’t always have the keys laid out with letters, and if they have letters, they’re in a different order sometimes. So if you normally remember your PIN as a word, memorize the number before you leave.
Missed the edit window. Here is AT&T’s International roaming FAQ. Yes, they do appear to still double bill for letting a call go to voicemail.
[URL=“International Plans: Roaming, Data & Calling Plans for International Travel | AT&T Wireless”]
Try to estimate how much you’ll be spending while you’re there- meals, drinks, souvenirs, taxis, etc., then exchange your money here into pounds, or at least write it down as a strict budget figure. (I’ve always taken my total in a money belt around my leg; never had any problems, and I avoided the ATM charges from both the UK bank and my own.) I found this is very helpful in stopping the natural desire to mentally convert currency when I’m over there. What I mean is, the first time I went, I noticed I spent a lot of time worrying about “Is this too much?” and I missed out on a few things simply because I thought, “I’d never spend this much on this item at home!” But if you can treat the trip like any other budget, you can get out of the “How much would this be in my currency?” trap as well as spend within your means.
I also try to listen to a radio in whatever country I visit, just to hear what is their current popular music. It’s not always what’s hot over in North America, so I always find that interesting.
Currency exchange places will though, which I think was the point.
If your phone is triband and unlocked it might be a good idea to get a local payg (pay as you go) SIM then distribute that number to your loved ones at home - much easier and cheaper to communicate with your local friend that way. Or if you want to keep your US number working you can pick up a simple or second-hand Nokia for about £10 and use that in addition.
Don’t worry about US$ or Traveller’s Checks. That’s old-skool. Just use your ATM card. However bring a backup card just in case you lose yours or it gets swallowed up! Your US credit card may not be chip-and-PIN enabled and may cause issues if you try to use it in stores.
You will find pretty much everything absurdly expensive compared to the US. It’s particularly good that you’re staying with someone as you won’t find the hotels good value, and in many cases they’ll be downright awful.
When ordering in restaurants, a little customization of your order is OK, but if you go all Harry-met-Sally on their arses they’ll probably screw it up or at least roll their eyes. Better largely to accept what’s on the menu, and then adapt it.
English people may come across as diffident but we’re actually extremely friendly, we just need some kind of introduction. People in the north of England are better at this than those of us from the south, who can appear pretty unfriendly. As said, it’s just cultural and if you do end up chatting to people you’ll find them pleasant and even curious.
When you do get talking to someone, “taking the piss” - the issuing of deadpan insults for humorous purposes - is quite common. Try to read between the lines and if someone appears to be mocking you, don’t be offended; gently poke fun back at them. It’s actually a sign that someone likes you - they won’t take the piss unless they feel comfortable that you can take it and it won’t make you dislike them. Unfortunately for Americans a lot of piss-taking is based on nationality; please don’t take it personally or as a direct slam - it’s just low-hanging fruit for some people.
The pub is the centrepiece of many people’s lives, and ‘stopping for a pint’ or ‘a half’ and a nice chat is a recreational activity in itself. I second the beer garden in the sunshine thing - one of the loveliest activities ever, particularly with a packet of salt and vinegar crisps or a pickled onion if you’re particularly daring. If you find yourself in Oxford on a sunny day, go to the Victoria Arms in Old Marston and have a pint on the side of the Thames amid the weeping willows and people gliding between its reedy banks on punts. Nothing nicer, and they do good food there too.
Re. electricity, I recommend the Fujifilm universal adapter (several different companies make them to similar designs, but that’s the one I’ve got). As stated it doesn’t convert the voltage but it is a good solid design and with the USB charger can be reused at home. As a rule of thumb most items which incorporate a transformer into the plug will be rated up to 240V (some of them say up to 220V but I’ve never had a problem): iPad, laptop, etc. However if you plug your hairdryer into such an adapter it will blow the fuse.
Enjoy!