I would offer you my old text books and CDs, but they only go up through level A2.
Not sure if you will be taking a laptop with you, but you can probably find some material on the Internet. I believe there are even some free learning software programs you can download that will even test you, etc.
There are also flash-cards available, to help you with your vocabulary (English word on one side, German equivalent on the other). I once bought a set of these flashcards in a book store here.