I've had outcalls to the Park Inn and Radisson Edwardian when flying out early from Heathrow. Neither has been any problem and the girl has come straight up to my room both times. This is a few years ago though, so I can't guarantee nothing has changed of course. Radisson Edwardian is usually more expensive than Park Inn but also nicer I think. That said, Park Inn is completely fine room wise for a punt. Can't remember how the receptions are and where the lifts are located but you may see that from a few pics at the hotels websites. Anyways, the girls had no trouble coming up to my room alone at either and the outcalls were both pretty late (Park Inn I think was from 10pm). Good luck.