I imagine the best way to learn a new language would be to be immersed in it, and that includes studying too. If the course is academic it would probably be tough, but something like graphic design or fine art would be easier if taught in German.
Why do you want to study in English? I've heard that some universities do cater for this but the costs for studying are much, much higher.
I'm moving to Hamburg in a few weeks and if I am unable to find work within a few months was considering studying again, and would relish the challenge of doing so in German!
Good luck with whatever you end up doing mate.