British ideally, but not essential
its a minefield out there, just too many profiles not sure which are reliable and not fake...
Might also want to add any services you want, age, size. If you want it a bit vanilla ie GFE then Madlin Moon I think is back in London in a couple of weeks you will have a good time she does a good GFE and PSE she is well reviewed and her incall is usually central London"ish". Plus you get to spend time with a porn star so if your new to punting that at least will be one off your bucket list of to do's.
There are others that I can think of but none come to mind that are well reviewed and central London. If you give a few more details I am sure we can narrow down your search so that at least you wont be taken in by fakes/Crap punts.