Well you have to be a bit more specific. Each country in Europe has it's own language so you have to narrow it down to one country and then start off early by learning the language. Perhaps doing some research work in a university in that country would also count a lot (especially since he's a professor). But I have a question. You say your boyfriend is a professor, so who's the medical student here? your or him? The entry requirements for professors and physicians are quite different. They undergo entirely different licensing procedures.