Brighton on the west coast of Sussex would be a good choice I think. It's a seaside resort surrounded by an area of outstanding natural beauty called the South Downs. It's possible to walk along the South Downs for 70 miles without encountering a town.
Brighton itself was built in the Regency style and has a long promenade of about 5 km which stretches into Hove and beyond in one direction and about 2km in the other. In the easterly direction, the promenade has a double decker feature so that you walk on two levels.
There are good shopping facilites to be had there and London is only an hour away by train just in case you do fancy meeting up with your fellow countrymen in Kangaroo Valley one day.
There's also a rail link to London Gatwick Airport from Brighton. Here's the Wikipedia site which might be useful to you: Brighton
Also, this link will open Brighton on Google Maps so that you can see where the town is located on the south coast: Google Maps - Brighton If you click the "Terrain" button top right, you'll be able to see the South Downs bordering the resort.
Brighton also has a yacht marina in case you're into boating.
Weatherwise, the south of England is much warmer than the north and places like Manchester can be pretty dismal in the winter. I grew up there as a child and can highly recommend it.
EDIT: for some strange reason, I can't get the link to work properly in Google Maps. But if you just type "Brighton" in the search field, it'll take you there.
[ Edit: Edited on 04-May-2009, at 10:03 by Blinq ]