UK companies can hire workers from anywhere within the EU without any sort of bureaucracy - EU citizens have an automatic right to work anywhere in the EU. The EU includes a number of low-wage countries with good numbers of skilled developers.
There is currently some amount of anti-immigration sentiment in many EU countries, mainly because of the recession. Governments can do nothing to restrict intra-EU migration, so tend to make life hard for non-EU migrants to look tough on immigration. The current British government is tightening quotas on non-EU immigration.
A British company is unlikely to even look at your CV if there's another qualified applicant in the pile, because of the cost and complexity of employing a non-EU worker.
There is no shortage of generalist developers in the UK and wages are significantly lower than in the US. Unless you have some specialised skills, your job search is likely to be quite arduous.