I'm an American who has visited the UK in five times, in 1985, 1989, 1993, 1997, and 2000, spending about a month each time. The first time, my wife and I rented a car for one week and drove all the way from Portsmouth up into Scotland and back in one week. The next two times, we also drove for a week, but we stuck to the south of England. By the end of the third time, I swore I'd never do it again. It was just too nerve-racking. (I did it 3 times because I kept thinking it would get easier each time. It didn't.) Since then, we have stuck to public transportation, or took day trips driven by my sister-in-law, who has a British driver's license. I have found it MUCH more pleasant.

It's not just getting used to driving on the left. For some reason, my wife had a tendency to drive TOO FAR to the left. Several times, while turning left, she ran over the curb. I found it more frightening to be the passenger than the driver. I was constantly afraid she was going to sideswipe a parked car, or dash me against a stone wall in the countryside.

Also, navigation is a problem. British road signs are different. Maps are different. Streets are laid out differently. You hardly ever find city streets laid out on a rectangular grid; they wind and curve every which way. Every three blocks or so, the street name changes. You can't tell by the street names or house numbers how far you are from anything.

Don't believe everything you hear. Someone (an American, I think) told us, "Roundabouts are no problem. If you don't know where to exit, you can just keep driving around in circles until you figure it out!" That's true only if you're on the inside lane. If you're in the outside lane, you're supposed to take the next exit. Cars on the inside lane will be moving to the outside lane, and expecting you to get out of their way. I think I figured that out on the third trip. No telling how many near-accidents we caused before that.

Country roads are narrower, often have no shoulders, and may even have stone walls right at the edge of the pavement. (I'm using "pavement" in the American sense; in Britain, "pavement" means "sidewalk.") Driving in the countryside is not especially conducive to sightseeing since hedges, stone walls, or embankments often block your view. And you will have too much on your mind to look around anyway.

And Britain has MUCH better public transportation than America, despite the fact that Brits complain that train service has gone to hell since privatization. And you can see much more from the top of a double-decker bus than from a car.