Since you have yet to go.....
GLS Sprachschule is in Berlin (cheap and fun)
and has a campus with its own apartment hotel
http://www.gls-german-courses.de/
Lessons are of course in German so if you would like an unfair advantage I recommend the following English/German books:
1. German grammar in a nutshell (by Christine Stief)...pocket book that explains all the grammar essentials up to B2 level. Best 14 euro i have
ever spent
2. Basic German Vocabulary (by Bock)
the 4000 most commonly used words, in example sentences. Learn the first 2000 and you will magically be able to understand newspapers and the news on TV!!
I passed the B1 exam with a 96% score. Just completed a month's intensive course at level B2 and found I was grammatically way ahead because of the nutshell book. Heading for the C1 exam (advanced)