Maybe they want to be some place that has a government that's going Big Brother? I dunno, but they should try to spread out a little more than the UK, though it could be convenient in travel time and the such. And maybe they don't want to be in the other parts of Europe. I dunno, I'm not them.
And it's not saying a million Poles are coming to the UK, it says that the gay community from Poland is coming to the UK.