What’s the legality of driving in a carpark...Watch
Good luck learning
Suppose if you closed it off to the public and you owned the car park you could probably do it, but then I can't imagine OP owns a car park or knows anyone who owns a car park, so it's sort of irrelevant.
you are not going to learn much in a car park, you need a good driving instructor at the start so you do not pick up any bad habits and you can build up your confidence. later when you are more confident you can then look at practising privately but initially i would defo get a good instructor with dual controls