If you expand ur search areas to London / East England I may be able to be a bit more useful. It is likely that other forum members can be more useful re: recommendations in this area.
I will add, going straight in a with a strapon is not easy. Anyone you do speak with, be sure to ask what sizes are available etc...you'll find many girls willing to stick things up your ass for a bit of money. Try not to be enticed by ones who:
1) will charge u extra for the pleasure.
2) are seemingly amateur enough that they'll just try and force it
be sure to have the time in the session to 'warm' to it....fingers/toys first etc...
Also, if you're wanting a mix dom/gfe session where you're wanting to have sex too, be sure to make sure this is available.
Having spoken with a WG who offered this, she mentioned that most men that want a strapon involved in the session end up asking to have sex first, then once they cum they dont really fancy the strapon so much anymore....on that basis, i would say maybe strapon first, then sex....might be a better option.