You would need to study for and pass 14 written exams for the theory, then take the practical tests.. a multi-commercial checkride in order to convert. You need I think 15 hrs according to the JARs in European airspace to convert the instrument rating. Check in the training forums on this site, it is covered extensively there.
Expect it to be expensive as hell, as well. And of course you would also be needing the right to work in the UK or EU if that is where you are looking for a job.
P.I.T.A
