I mean you don't particularly need notes for English, Math or Modern long term. As longas you understand the text you're studying and have drafted for english, you'll be fine. As long as you do practice questions for Math and know how to answer questions, you'll be fine.
You don't need notes for Math or English.
For Modern History, you will need notes in the short term. But don't worry about it if you haven't taken notes or memorised stuff in year 11, it'll be different and unrelated content in year 12 anyways. The only thing you need to retain from prelims is the ability to be analytical and answer source questions.
Sorry to say but for ecos, bio and legal you'll need to memorise a lot of stuff. Just do this periodically, pay attention in class, revise your notes every so often.
Last tip, if you have pages of notes, get rid of the useless info. Just accept the fact that you can't learn everything in any subject save math. For math it's a strict logical reasoning so anyone is capable of learning all the content relating to their specific units of math. For every other subject tho, such as ecos, modern etc just accept you can't learn everything and focus on the important and key points. Make briefer notes.
It's better to learn a little less in a lot more depth then trying to memorise everything, because quite frankly unless you're 75 years old and have specialised in World War 1 for the past 50 years, and even if you have, you still won't know everything on that subject matter.
So yeah, have fun, keep your goals realistic, don't bother trying to learn everything. And I'd recommend dropping one of ecos, bio, modern or legal if you're struggling with workload since they're all quite content heavy, although I don't particularly know how well you're doing in them so I can't give any specific advice on that matter.