How will these all fit into my backpack?

[Matterhorn Fan]

The photocopy option is a good one then (so long as you can predict what you'll need when). Copy double-sided.

See if any of those texts are available in paperback editions (unlikely, but you never know until you check). If you can find a reasonably priced paperback, that'll save you a few pounds.

If any of them are things like writing handbooks, you might be able to get away with a different compact edition. You'd be on a different page, but the rules of the comma are the rules of the comma. All those books are essentially the same, unless yours is full of exercises you will have to complete during class.