Thanks so much for the response, I hadn't thought it through but to be honest I'm quite vanilla when it comes to punting, so I'd be happy with anyone from 18 - 45, any hair colour or style, and size wise thin to BBW (though over size 20 would have to be fairly cheap). Owo or Ow is fine, and well yeah, as long as they're friendly, inexpensive and that feedback was guaranteed that's all that really matters (and I guess facially above a 5/10, so not anyone who is terrifying!) but I'll definitely try what you suggested though and go through reviews here and look on AW to see who seems reliable on the feedback front.
Oh yeah, area wise, anywhere near a tube station would be good (or, you know, a 10 minute walk rather than 30 minute one), Zones 1 - 3 would be easiest, but I'm prepared to go out towards zone 6 if need be.
Edit: Just to add, my perfect girl would be English, slim, in her twenties with D cup natural breasts who loved to dfk, deep throat and would swallow, but that's who I'd be prepared to pay £200 for, and right now I'm happy to go with anyone as long as they're friendly and not a GILF.