If it's just a massage course, which is mostly about practice anyway, I'm sure you'll get by with basic German. Even if you don't speak much German now, your understanding of the language will improve and you will speak more German by the time you finish your course. If you're as serious as taking classes to be a certified masseur, chances are you'd work in Germany and have to speak German with your clients anyway, right?
If you're really really really really really really really really against learning German and insist that the course must be in English, then look up http://www.expat-blog.com/en/nationalities/british/in/europe/germany/ and check out what the English speaking expat community in Germany has to offer you.