The Totem studio is in Paris, and France is a lot closer to multi-racial London than even the Czech Republic. Moreover, the Euro is currently strong against Sterling. So, advertise in a London-based young women's magazine for pretty girls: no experience needed, all races considered, likewise big boobs no less than tiny tits. Hire a cheap flat in south London for the interviews. If you can't spare a team member for the interviews, hire a local Dirty Old Man (me, for instance) to conduct them. Those who pass get a choice of economy flight or Eurostar to Paris, one-to-two star hotel while there, whatever the fee is, the promise of more work if they go down well, plus their details being made available to a variety of trustworthy agents, who may (or may not) contact them.
Then await the avalanche.
I am a DOM of total integrity, but even if I were not, how many times a week could any normal man apply the casting-couch?