OK, as you seem to be new-ish, and no-one else has replied, so I'll bite...
This is how it works.
Go to AW search page. Select female, escort, select age 30-50 (or whatever), select East of England, then Hertfordshire, select nationality British (UK). (You will need to do a separate search for SE/Bucks/Hemel).
Doing that I got 50+ incall options, many of which had a reasonable number of AW reviews (so they probably exist) and some obvious known-names. Read their profiles, then cross check any you fancy using their AW profile number on UKP to see any reviews here. Maybe then ask any specific quesions about an SP.
See the escort. Write a UKP review. Get some brownie points.