I'm also from E.Europe and I was in similar position. Was contracting as php dev in UK/London, then moved back to my home country. As someone suggested, the best thing is trying not to be 100% programmer, but also have a little bit of business acumen and trying to get to know companies/people in London while you're there. This way I managed to do some remote work (same rate as on-site). Some companies are willing to pay you well as long as they know you personally and have experience what you can do.