wow, quite ambitious......i really wouldn't venture to buy a biochem book, b/c it'll just end up as a door stop, or possibly a really expensive log for your fireplace. There's a few good books for CTB (Cell and Tissue Bio), but I don't know how high yield they'd be for a "brushing up".......they're pretty dense, and well, you should just enjoy life right now before the real "brushing up" begins. Plus, there's a good chance that your big sib will hook you up with some books, so you might want to wait.
Nonetheless, if you're still gung-ho about it, send me a PM and I'll getcha some more info. As mentioned by my colleagues, the Kierztenbaum book and the Klein "basic concepts" books are good starts. If you want to be venturous, I'd also recommend "Pre-Test" by Klein and Enders.......but, seriously for the love of humanity, don't start studying now