when I first moved to the UK in 1993, DH had a jag. I hated it because I had always driven small cars. I had been driving in the US for nearly 30 years, but driving in the UK scared me.
So I took a few lessons as others have said, designed to teach me to pass the test. I passed on the first try, and never looked back. In the US, I drove in LA, NYC, Chicago - you name it, I drove there at one time or another. Cities are in many ways easier to navigate than a small town. You want scary? Try driving in the Algarve (Portugal).
Even if you do plan to go back, things have a way of changing. And while you are here, that US license is no good after 12 months. Its £50; you won't regret spending it.
We have a car that we rarely use as we are in-town and can walk practically anywhere. BUT - when we need the car, we have the car so we have a choice.
But at the end of the day, do what you are comfortable with.