If you spend some time in Bath (well worth it) there are also many tours including Stonehenge and other monuments.
Here is just one company, Google has many others.
http://www.madmaxtours.co.uk/tours/stonehenge-full-day-tour
Similar thing for York.
http://www.visityork.org/thedms.aspx?dms=11&groupid=5&catid=7&itemtype=17%2C287%2C311
Looks like you’re covered re Aug/Sep, so I’ll ask a question or two…
You said you plan on some day walks. Do you have any plans for those? What is your walking level/experience? Are you OK with hill-walking? A bit of light scrambling (“one hand down” kind of stuff)? Are you OK with map/compass and GPS?
I would go in September too. Avoiding everywhere being crowded is much more worthwhile than a slightly better chance of nice weather.
My favourite places in the UK to visit are Greenwich, Kew Gardens, Winchester, Oxford, Blenheim Palace and Bath.
Trains are good for moving between areas and buses are good for moving within urban/suburban areas, but if you want to get out into the countryside proper you probably need a car.
The problem with great houses in the UK is that there so many!
Too many to see so pick a few of the best. (look at the natural England website.
But Blenheim palace and Chatsworth house will start you off.
Hi all! Back again 
Wow, heaps more information and tips. Thank you all very much. I had heard that Avebury might be a better bet than Stonehenge - I will have to look into the tour company though. I really appreciate the time people have taken to rustle up links.
People have given us something to think about as regards public transport versus car. We have been thinking public transport in regards to meeting and chatting with fellow travelers, and if not driving, both people can take time to watch the scenery, instead of having to concentrate on the road. Anyway, we will give it more careful consideration. I believe we would be eligible for some sort of tourist pass.
Re: walking. We are in our early fifties, both fairly fit. Our intention is to use the next 7 months to improve this. We took our first walk this weekend just gone - 8km (hilly) in a bit under 2 hours, and pulled up well (is this good/bad/indifferent for a first training walk?). My husband is proficient with a compass, and both of us are good with maps. However, we do not particularly intend to do any really challenging walks - we are thinking more point to point walking, maybe 20 km in the day style of thing. We are thinking more about seeing scenery along the way, rather than focusing on covering a huge distance, or completing a difficult scramble.
There are plenty of coastal paths where you can’t really get lost, just keep the sea on the left! The South West Coastal Path has many spectacular sections. The only problem is that you never end up back where you started, unless you want to do the whole 11 thousand miles :eek:
Bear in mind that Stonehenge isn’t just the standing stones. It needs to be seen in the context of the surrounding landscape, the barrows, cursus and so on. I haven’t been since they built the new access arrangements and visitor centre (anything would have been an improvement), but there’s a walk from Amesbury to Stonehenge that approaches the stones via a line of barrows, then down the cursus and up the slope, and there’s something magical about the way (from that angle) the stones just appear on the horizon. Likewise, that walking route goes up the slope behind the stones, and they just disappear in the same way. It’s perfectly possible to do this by train to Salisbury, from where you can get the special bus direct to Stonehenge or a local bus to Amesbury for the walk I did.
Starting at a reasonable hour from London, I had time to get back to Salisbury for a look around the Cathedral and its copy of Magna Carta as well.
OK, you sound pretty well set up to tackle most terrain anywhere in the UK. Steer clear of the big peaks though, like Helvellyn (Lake District) or Kinder Scout (Peak District). They’re great, and not hugely difficult, but something like the Striding Edge route up Helvellyn can be a bit pants-changing in high winds, and they can get a bit rammed, even in September.
England is absolutely festooned with public footpaths, bridleways and BOATS (Byways Open to All Traffic), and they allow you to roam freely over vast swathes of the countryside. The fantastic thing about these is that you can walk for hours on them and hardly meet a soul. Once you’ve decided roughly where you are going to walk, buy the OS (Ordnance Survey) maps for that area and these paths will all be clearly - and mind-bogglingly accurately - marked. Go for the Explorer versions which are 1:25000 scale. Well worth getting the waterproof versions too! You can buy maps by region, or you can create custom maps, and you can even pre-plot your route online and load your route to your GPS. All info available here:
Prepare yourselves for mud. Even if we have a dry summer, a day or two of rain and a lot of paths can become quagmires, especially the bridleways (open to walkers, horses and cyclists) and BOATS (same as bridleways, but open to off-road vehicles too). Try to plan your route mostly on footpaths (pedestrians only). You might meet some overgrown paths too, so perhaps be prepared for pushing through some brambles.
There are plenty of well-trodden trails you can stick too, such as the North and South Downs Way, and the Pennine Way, but for me, the great thing about walking in the UK is plotting my own route on the roads less travelled by.
Or canal towpaths can also be a great way of seeing the countryside - and they’re nice and flat, except at locks!
In Scotland you can walk along the Forth & Clyde and then the Union Canal between Glasgow and Edinburgh, or choose a section like Linlithgow/Falkirk - one end has a very historic castle and the other end has the Falkirk Wheel, a cutting-edge engineering project joining the two canals (which arrive at Falkirk at substantially different levels).
There must be innumerable suitable walks around Britain so good luck making your choices!
With the added advantage of it being nigh-on impossible to lose your way on a towpath!
I tend to see much more wildlife on towpaths too; I once spent a very happy half an hour watching a Kingfisher flashing up and down the Kennet and Avon.
… and I so want to sail a barge on the Falkirk Wheel.
Also consider combining a walk with some sightseeing. This would be easy in the case of say Chatsworth or Avebury.
They run regular tourist boats from the bottom pool, through the Wheel onto the Union Canal for a short stretch, and back down, which takes maybe 1/2 hour or so. But I’m sure taking your own boat through would be much more of an experience!
And a couple of miles further along the Forth & Clyde, just before it meets the river Forth, are the Kelpies, giant, 100 foot high metal statues of horses’ heads. Impressive.
Cool. I’m off walking in the Outer Hebrides this September. Might try and fit in a visit on the way there, or back.
Personally I wouldn’t bother with a tour company to Avebury- it’s a village, there’s a local bus from Swindon. There’s already a museum and plenty of signage, so I’m not sure what a tour guide would really add to the experience aside from a bill and a time limit. I’m generally a fan of disorganised travel though!
Also, just to add to the general transport suggestions, for shorter distances UK coaches can be perfectly good, and often far cheaper than the train (the two major companies are National Express and the, often cheaper but slightly less reliable, Megabus). I would not suggest long distance travel with them, as they’re not so comfortable, a bit slower and tend to stick to motorways, which are largely pretty dull, but for a few hours trip they’re fine.
Another good walk would be along the central section of Hadrian’s Wall. You could stay somewhere like Haltwhistle for a couple of days, get the AD122 bus to various points of interest along or near the Wall, like the Vindolanda museum, as well as walking alongside some of the more dramatic stretches of the wall. Or there are loads of companies that will provide guidebooks, book B&B and transport your luggage for you (another option on most of the best-known walking trails).
This is on the itinerary my next UK trip, hopefully next year - this plus the New Forest.
My wife and I have just migrated from Oz to the UK, and have settled in London. We’ve started working, so haven’t seen much of London or England yet, but when we came over we did however spend over a month up in Scotland first and I recommend spending some time up there.
In particular I would recommend the following;
Urqhart Castle I thoroughly enjoyed - because we were touring around in Winter (November/December) it wasn’t at all busy and I wound up with a one on one personalised tour around the castle with a very knowledgeable tour guide.
We hired a car a spent some time in the Highlands and two drives in particular we were very impressed with the scenery.
Drive from Glasgow to Fort Williams, in particular near Glen Coe there is *Bidean nam Bian *also called the Three Sisters.
Drive from Fort William out to Mallaig was simply spectacular, it took us about twice as long as the GPS stated because we kept stopping at all these lookouts to take in the views and take photos. To be honest Mallaig itself was a bit disappointing, not all that much to see in the village itself.
We didn’t do it, we only found out about it after we got back to Glasgow but there is a ‘new’ route that’s been opened called the North Coast 500 Which I have to imagine would be spectacular.
One thing we didn’t really enjoy,
A few other bits and bobs worth a look, (if you like some historical stuff)
If you are anywhere near Bamburgh, and Lindisfarne during your travels then I’d highly recommend stopping by.
The beach there is as beautiful as any I’ve seen the world over and the causeway to the island is always fun.
Bonus marks if you grab yourself a kipper from Craster as well.
Well, as I said, the good part of taking the tour was being able to walk inside Stonehenge itself and touch the stones, something you can’t do if you just go there. There’s an armed guard to make sure no one commits vandalism, but he was fairly unobtrusive. The tour guide gave a fairly extensive lecture on the history and archaeology of all the sites, which was very interesting. No matter how you get there, though, be aware that most of the Avebury stones are in the middle of a sheep field, so watch where you put your feet!
If you get out towards Wales, I can recommend the city of Conwy and the nearby Bodnant Gardens. Conwy has a lovely restored Tudor house (Plas Mawr), as well as the verified smallest house in Great Britain. Bodnant Gardens is just plain lovely. September means you won’t get to see the Laburnum walkway in bloom, but the gardens are stunning. They have a sequoia there brought back from CA that’s been there since before the USA *was *the USA. Near the English/Welsh border is Hay-on-Wye, a town that has loads of bookstores, many specializing in second-hand or specialized books. It looks like the number has declined, though, which is too bad. 
Meurglys was one of the Dopers who acted as a tour guide for me. He and his SO did a kick-ass job of showing me about Edinburgh, and even if he doesn’t have time to guide you, make sure you meet up with him. He’s good people.