See, I had a problem like this in the U.S. I was only going to Missouri for one year as an AmeriCorps member, but PA law says you have to change your residence within 30 days of moving. I still considered my parents' home my permamnent home, so I didn't change my address.
I assume this would also apply to students going away to college. I wonder how many would actually change their address?
In a way I can see the point about not getting a UK license, if you aren't planning on being permanently settled and you only rent a car once in a while it seems as if there should be a separate category.
But there isn't so people should really get their UK license.