And on whether you should actually do this:
I'd suggest just getting to grips with the basic terminology and stuff and making sure you know that, so that when it is taught you understand and can take it in first time. My main problem from not reading beforehand wasn't that there was too much material or that I'd regretted not starting earlier, it was just that I didn't understand the stuff they were talking about in lectures when they said it. So get to grips with terms like dorsal, ventral, inferior, superior, rostral, caudal, lateral, medial, anterior, posterior and stuff. I would say make sure you enjoy your summer holidays, but definitely feel free to get to grips with the most basic parts and get a general overview before you start :-)