If you are not getting enough traffic in a particular area, it can be worthwhile to close it down completely - preferably temporarily - and then come back to it with a targeted launch at some future time once the core regions are self-sustaining.
So for instance, you could organise some UK-centric marketing, with some PPC, etc., and maybe go speak at some UK events or something around the same time. This will hopefully get you a critical mass of interest in a short period of time, while in the meantime you get to focus on your core demographic.
Otherwise you can end up wasting a lot of time on stuff that isn't working for anyone - if you don't have enough candidates and recruiters in the same place at the same time, those people are potentially just going to go away with a bad impression of the service, so in the long run you actually lose potential clients.
If you can get that same number of people onto the site in a month instead of over the course of a year, it'll work out much better. If you leave it entirely to organic growth, that probably won't happen.
+44 (0) 111 1111 111
I had to enter 1111111111 to get past the validation.
All of this said, we hope to not be in the contingency recruiting business forever. We feel that there is a friendlier fee structure to implement (with better incentives for companies and candidates alike), which we will do as our marketplace grows.
RE: UK jobs, most of the companies who have signed up are in the Bay Area and NYC right now, but there are no strict limitations to prevent UK companies from participating. We do have candidates in the UK that have signed up, FYI.