What stops people from outside the country from contacting the UK branch? Games aren't local like that, I'm sure these guys work with tons of people from abroad... I don't see how that could be it.
Nothing. But then again why should they? It's harder for them (compared to some other platforms) and they would have to work with a platform that they don't want to. Compare their approach to Sony's. Hotline Miami is coming this summer to PS3/Vita. Housemarque has made Super Stardust exclusive to Sony platforms. Even Avalanche had PS3 exclusive functions in JC2. This all is because Sony operates in this area. Sometimes you need to go to the dev.