I still have my old plates...I've never heard of turning them in???
I also have a VA license, since that's my 'official' permanent address (parents live there), but I haven't LIVED in VA ever...I'm in Texas at the moment, and I drive a VA-registered car with a VA license. The car is slightly dodgy, because the inspection expired in May, but the car hasn't ever been back in VA since then to get it renewed. I can't register it in Texas, because I don't have a permenant address here, plus I am not the owner of the car (my parents are). Same for the license, though it has caused me some hassle! I've gotten denied buying liquor (and questioned a few other times) twice now for an out-of-state license from some over-zealous clerks, which has been annoying.
From what I understand, as long as you have an address in that state that you can call a permanent address, then you are entitled to a license. So even if you reside in the UK, if you've got an address somewhere you can use (a house you still own, or maybe your parents), then there shouldn't be a problem.