I don’t have enough time to buy GBP from my bank so when I land at Heathrow should I go to the closest ATM and pull out a few hundred pounds or exchange them at the airport?
ATM is certainly going to be your best bet, but just make sure that your debit card (tied to your US bank account) is set up to allow you to use it abroad, as sometimes the PIN numbers are set up a bit different in Europe (more numbers needed in your PIN as I recall).
Call your bank and get any needed details from them, and have a great trip.
(in general, currency exchange booths are NOT a good deal at all)
This is especially true, in my recent experience, at the San Francisco aireport when I went to Japan. When I saw they were offering less than 70 yen to the dollar I walked on by and after landing changed some money at the booth in Narita (over 81 yet per dollar). The rest I needed I got at the post office ATMs (the only ones in Japan that take foreign debit cards - plus 7 -11 stores) and got the best rate there, or using my debit card as a credit card to pay for stuff also gave an excellent rate.
Roddy
I was told it was best to use an ATM as you will get the current exchange rate, whereas the exchange booths in the airport will not cut you a good deal.
ATMs by far. Currency exchange booths are really hit or miss. A few will give you a good deal. But many, especially at the airport and in touristy areas, will rip you bad. I recently went to France and changed about $200 at Charles de Gaulle, just so I’d have some cash on hand for tips and small purchases. I got 130 Euros back. So with commissions and fees I ended up paying more than $1.50 per Euro (the official exchange rate at the time was about $1.25 to the Euro). One place near Notre Dame reamed me with a rate of close to 2:1.
I got most of the rest of money through ATMs and even though people told me that was the best way to go, I still had a nagging fear that they would rip me off in the same way. But when I got home and checked my statement, I saw that what they gave me was pretty close to the official exchange rate , minus about $3 or $4 in withdrawal fees of course. You might want to check with your bank to see what they charge for withdrawing money overseas, but even with a few bucks in fees it’s totally worth it and you end up saving a bundle.
I had always thought ATMs were the way to go, too, but on my last trip to Europe in July, my bank (B of A) gave me good exchange rates, but hit me up with a $5 fee for every cash withdrawal I made! And I didn’t find out about them until I got home and got my statements. 
So check with your bank about foreign ATM fees before you go.
FYI, I was in UK, Czech Republic, Austria, and Hungary, and it was the same everywhere.
ATM all the way.
Last time we were in Europe our trip happened to fall over the month-month break. This allowed us to visit the ATM practically every day. We used cash to pay for hotels when we could.
Now that Credit Cards charge a 3% fee on top of an unfavorable exchange rate, ATMs are your new best friend. (Last month I was in Canada. ATM exchange rate turned out to get better than a dollar from an ATM. I also made one credit card charge – ended up getting less than a dollar per US$).
ATM!
Sorry to hear that.
There are two types of ATM fees: the ATM Bank and your Bank.
The ATM bank charges you because you aren’t their customer.
“Your Bank” rarely charges, but I know nothing about B of A. If B of A charges, then you should get a different bank. There is no reason for them to be charging you, unless they are merely passing along the ATM Bank fee. I think some banks do, but they suck.
I’m happy with my bank, that doesn’t charge me ATM fees, and refunds me the ATM fees charged by ATM Banks. 
Bank of America has a program with several common banks - in Europe these are:
Barclays (UK, Spain, Portugal)
PNB Paribas (France)
Deutsche Bank (Germany, Poland, Czech Republik, Spain, Portugal, Italy)
For credit cards, I’ve had very good rates and no fees from Capital One, although this may have changed by now. Credit Card stuff has been in a bit of a flux.
I think the cheapest is going post office
how does that work?
As I mentioned above, I too had to pay fees when I went to the ATM, but didn’t mind it, because it was still a lot cheaper than going to an exchange booth. The trick is to get as much money as you can each time you go to the ATM (assuming you’re comfortable carrying a lot of cash) so you can keep your withdrawals, and thus your fees, to a minimum.
And when you use an ATM in a public place like an airport, be especially alert for pickpockets. They stake out the ATM, and when they see you’ve received cash, they’ll hit at the first opportunity. And yes, this is the voice of experience.
Definitely ATM, but make sure your bank knows you’re going outside the country (also notify your credit card company). First of all, you’re going to get the best rate possible. About a year ago, it cost me $30.93 to get 20 euros, which at the time had an official rate of about $30.
Airport/Train station money exchanges are very poor rates, but sometimes you need to use them (e.g., to pay for a taxi). Just exchange what you need immediately and get the rest at an ATM.
My credit card did charge a small fee per transaction, but it was still the best way to go. You did get the best possible rate.
Definitely ATM. Once you’ve got the money, you can also just buy a cup of coffee or something small from the stores in the airport to get some coins and smaller notes in case you need them. Also, don’t panic if your card doesn’t seem to work for whatever reasons. Walk around and find another machine from a different bank and try again. This happened to me in Heathrow as well as a couple other times when trying to use my ATM card internationally. There are machines from different banks in Heathrow, so it shouldn’t be a problem.
Sorry to wake up this zombie, but the many posts above have convinced me that if one wants foreign cash, then the ATM is the best. But I still have some related questions.
I (an American) will be driving to Canada for a few days soon. Several options are possible: One is to avoid Canadian cash entirely, simply using my debit card anyplace that will take it, and use American cash elsewhere (like hotel tips). The alternative would be to withdraw some cash at the first Canadian ATM that I see, but I’m worried about what to do with whatever I’m left with at the end of the trip. For example, if I’m left with $5 or less, I suppose I could just spend it at a convenience store on the New York side, or just accept the loss. But what if I’m left with $20 or $50 or more? Can I just enter a bank and ask them to change it? If yes, would American or Canadian banks be better for this?
About exchange rates: I checked with my bank, and they are totally up-front about their fees: If I withdraw cash at an ATM, the fee is $5, but if I use my debit card, there’s a 3% charge. Now that makes the math pretty simple - for less than $167, the 3% is cheaper, and for more than that I’d be better of withdrawing the cash. But that presupposes equal exchange rates. Is there any way to know what the rate is at the time of exchange? In other words, if I spend $100 at a Canadian place and run my card through the register, is there a way for me to know what exchange rate will be used? If it is a bad rate, then I’d be better of withdrawing the cash at an ATM, even though the fee is higher. Then again, I can’t really make these comparisons unless I know the ATM rate as well. And I’ll bet that the rates at the ATMs of different banks will be different.
Thanks in advance!
If you’re going to places close to the border, the businesses usually take USD with a posted exchange rate that is usually quite favourable (we’re so close to par right now that it will probably BE par). If you don’t like those rates, then go to an ATM, I guess. We try to only use credit cards when we travel - VISA does exchanges on currency very well with no fees at all (if I recall correctly - it’s been a year or two now).
You can look up exchange rates online - the rate you’ll get is when the transaction goes through. In my experience using my Canadian credit card online, the transactions usually go through in a day or two, so the rate isn’t exactly the same as when I purchased something, but close enough.
You should be able to cash in any of your CAD at a local bank when you get home, or you can do what we do - just put the money away for the next time we visit the US. At least when you put CAD away, it’s increasing in value, not losing value like the USD that we put away. 
Got to disagree with the general trend towards ATMs as the best deal. On a trip to Canada in July I compared the ATM fees with what I got from a local bank:
(100 US into CAN cost $2 US at a local bank teller vs. $6.50 in ATM fees; these exchanges were done within a week of each other, neither at an airport or other transit hub.)
YMMV, but ATMs are not hands-down always the best deal. It may be better to just walk into a bank (not at the airport) and exchange cash.
In answer to the Post Office being cheapest:
The Post Office offers commission free currency exchange. However that assumes you have the cash to start with. Plus I’m not sure how competitive their exchange rates are. It may well still be the cheapest method though.
I use a credit card which practically has free cash withdrawals anywhere in the world (well, it’s £1 per month for as many ATM transactions as you want), and a near-perfect exchange rate. So for me that’s cheapest. But be warned that most credit cards charge you lots more EACH TIME you use them. So if you pick the right credit card, and make sure you pay off the full amount every month, then that’s as cheap as it gets in my opinion.
The ATM.
Exchanging at the airport loses a huge amount of money. It’s something I only do in really rare occasions.