If you've driven in the states before driving here is a breeze. Well it will suck if you don't know how to drive a manual. I'd suggest an automatic, unless you can't afford petrol. The written test is a breeze, because the test questions are the same ones you see on the study dvd. If you fail the written test first time, you're an idiot. Actual Driving test is not any harder, just longer. My wife and I both passed first time (manual for me, auto for wifey). I even passed my motorcycle test first time here, in torrential rain even. So take a few lessons and you'll be fine. I'd suggest driving here on your american license at least a few months though before you take lessons.
It may have been a breeze for you, but everyone is different, and many people, including myself found it very difficult. Many people fail the theory test, and I can assure you, they would be pretty unhappy at being called idiots. Just think about how others might feel before you post.
I agree with racheeeee.
As the majority of posts on this thread have already testified, in general many people possessing many long years of safe, confident and fully competent driving in the US find it very difficult and even initially frightening to perform the very real brain-switch of driving in the UK, and that's not to be put down.
Not only is there a brain function switcheroo in which not only the road but the vehicle is mirror image to what one is used to, but signs, road markings and even lane stripes can be sufficiently different as to cause not just confusion but even fatal mistakes in rare cases.
To some it may feel like a breeze, but anecdotal evidence points to that being a minority fortunate few. It seems that most find it at least initially very daunting to accustom themselves to driving here. Conditions can be very, very different -- roads are narrower, more organic, junctions are not always neatly "grid" and can be confusing, roundabouts are virtually non existent in the US.
Ive heard it said more than once, by friends of mine, that in fact it's easier for a UK-experienced driver to cope with driving on US roads than vice versa, not least because US roadways in most places are usually on a grid-plan, easier to negotiate than the ancient-origin roadways of the UK, wider, and so many other reasons. The US roadways were purpose-built in a young country, for driving convenience. UK roads were not.
There are many elements that make the US to UK switch far from a breeze for most, and that's in an automatic, not just a manual. Intelligent and capable people here have found or are finding the experience daunting, and nc73's post manages to crap on that without justification. Nobody is an idiot for failing either part of the test, theory or practical. It's a pretty exacting test, famously so, both parts. Give respect to those who have to get through it.