I haven't done any courses there, but know the professor chap. He's a great guy, speaks fluent English and knows loads of dirty jokes. Have no fear! If in doubt, why not attend the Jazz Baragge: every Wednesday night they have free concerts from the Jazz Students (no Jazz cigarettes, though) to give them the opportunity to perform in public. It usually starts around 9.00 but heats up after - well, it's Jazz - midnight.
http://www.jazzbaragge.ch/ Should you go - and I recommend it - ask the friendly bar staff who's 'in charge'. Very friendly atmosphere, easy going and great music. A good lead if you're considering a course