This past summer I rented a car for the first time in the UK. At the Bath train station, I asked a taxi driver if she would give me an overview of some basic adjustments . . . roundabouts, narrow streets and right-of-way issues, emergency vehicles, pedestrians, et al. She took me on a 20-minute drive, and was very thorough in her explanation. Then, she waited for me at the rental car place (at no charge), then had me follow her to my B&B. It was an excellent introduction to driving in the UK (I tip I got from this forum).
The first couple of days were pretty stressful . . . I was constantly thinking about my driving . . . very little seemed natural. Being a tall guy, I had rented a medium sized car . . . that may have been too wide, as my wife was certain I was going to scrape the right-hand mirror on walls and parked cars (never did, but she swears that I was within an inch).
I got more comfortable as time went on, but there wasn't a day of driving where I didn't have to really focus , especially when in a busy four-lane roundabout or when the GPS was telling me to turn, but if I did I would be going against traffic (which happened in Durham . . . there was a lot of honking then). It wasn't that the GPS was wrong, it was just that I needed to turn at the NEXT street, which was about 30 feet away.
We saw so many places that would have been difficult, or at least not time-efficient, to see using public transportation. I'm glad I chose to drive, even though the stress did take some of the fun away (and at least a "divorce" didn't come up during our escapades).
I'm planning on a trip to the south of England in a few years . . . by car. So, I get it wasn't too bad. Of course, I haven't run that past wifey yet.