While you will be surrounded by the language 24/7 once you have arrived here in Germany and hence will “have no choice but” to learn the language along the way, attending a German language class will ensure you learn the proper grammar and pronunciation. If you would like to brush up on your German before arrival try using an online language learning system like Rosetta Stone, go to your local library to check out whether they have any German (childrens) books in store, search on the Internet for a free  German web radio station, read German magazines or newspapers online or rent a movie you already know by heart and set the language to German this time. There are many different ways to practice German even before you get here.