What kind of bag should i get for med school?

Whatever bag you want. I used a backpack. I carried no books with me whatsoever - used whatever I needed in the library. Just carried paper, notebooks, stationary and occasionally my laptop (but I hear students don't really use paper for notes much these days so you might just need your laptop).

no way- I thought you had to carry like 10 textbooks, my shoulder still hurts from all the books we had to carry in sixth form, thanks!

I mean, you are welcome to carry textbooks if you want. You won't need them in lectures though. I carried around way more in 6th form (and even more at GCSE) than I did at uni.