The UK is nothing like full. London and the South East may be over-populated but there's huge tracts of the UK that aren't. As long as anybody coming in pays their way then its all good and can do nothing but improve the homegrown feral gene pool. IMHO, like.
I heard on the radio that you could (shoulder to shoulder) fit every human being on the planet onto the Isle of Wight. Puts the over-population debate into context.