Hey pistolero, you could fire off a few rounds of your 'pistola' at a sex party in C London, if you don't mind a Roman Orgy situation. You get to share 7 hotties with some other like-minded guys for 2hrs for £160 or 4hrs (2x2hrs with 1 hr break in between) for £260, though they usually milk me dry in 2hrs.http://www.ladymarmaladeparties.com/hostesses
Toni aka Karlie Simone, Delilah Dash & Delta White fit your description of British Blonde Bombshells with fake hooters, all are published pornstars. There are lots of other equally hot 'amateur' girls there from all around the world.
I've met guys there from the US who route their business trips to Europe via London just to attend. Apparently there's nothing like it back home.
You don't need to book until the morning of the party. If you enjoy it, you could easily return a few more times later in your stay given your budget.