there's another wrinkle or two. Insurance companies here in the UK will charge more if you are driving on a US license, so you are much better off getting the UK license ASAP.
Also, be aware that your former state of residence may require you to inform them of any change of address within 30 days. Some states, like Virginia, automatically CANCEL your license if you move outside the US, so you could be left with no license. Virginia very quickly sent me a letter canceling my license this past summer, but there was NO mention of this on the DMV website. Luckily I still held a valid UK license, and just had to update the address and submit the forms and picture to update it.
I first took the UK test in 1993, at age 46. I had been driving for 30 years. That was of course back in the days when the 'theory test' was a few verbal questions by the examiner after the 'road test'. Plus, the vision test was a simple 'read the letters/numbers on the number plate of the xxx car that is parked over there'.
You biggest issue regarding driving on the 'other side' may be driving a car with manual transmission if you have always been used to an automatic. Aside from that, get in, and make your sure your 'driving mantra' is "KEEP LEFT". Post it notes on the dashboard aren't a bad thing either.
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I took 3 or 4 driving lessons. The objective was not to teach me to drive, but to teach me how to pass the test. And I did, first time, no problem. It was a good investment because the instructor had me driving along the typical routes that would be used, and made me aware of the situations that would require a response.