So this is in the Croydon vicinity?
Do a search on AW girls in the area (5 mile radius?) and post up links to a few that you fancy who can do Outcall. So you fancy Black, that narrows it down a bit too. And you'd need a girl who has MMF or Moresomes or gangbang in their AW Enjoys.
You could perhaps even book the girl on your own first, to make sure she's any good, perhaps just a 30min booking? And write a review to gain cred. here.