So far I've only been to the London environs, and that was when I was in early high school. A good trip, but a bit wasted on me then. London is interesting to see, but hardly a way to see the real face of Britain I'd suppose -- much as if someone were to come to the States and judge me by how he was treated in NY. :/
Even in the Old Smoke, though, I found the English to be friendly to us, and I had a good visit. Plus, got to remember that us yanks don't have any cities that were founded by Romans... When I go back I'll get all around Britain and into the country, and that'll be fun. =) My brother went to Ireland and Scotland when he last traveled, and he had a blast. (and a few drinks too.)