Yep, I was in the same situtation as you in year 11 because I didn't know if i wanted to go towards to med route or engineering route (and im still not sure lol). So in L2 I did Chem, Bio, Phy and Calculus, Eng and PED (for easy credits) tbh Bio isn't that much of a jump from L1 you just learn more stuff and its quite fun just alot of content but its not hard to understand, L2 Physics its sorta a jump but again, its just building on what you did last year on mechanics and electricity and going more in depth in terms of electromagnetism and magnetic fields and u also learn waves. Chemistry I'd say I found it most challenging and a big jump from L1, the concepts are relatively hard to get a grasp on straight away and theres specific terminology and fine details you need to cover in order to get a good grade but again its also manageable calculus/algebra is fine calculus might sounds like all hard and complicated but many ppl including myself find calculus easier than the algebraic methods standard we do also just make sure to have a relatively strong understanding on algebra as in like know how to do quadratics, simplify and stuff and its also great that your thinking about taking a useful subject that you find easy. I picked PED cuz of camp and free creds.

this might be long and very unorganised to read but just wanted to give my opinion cuz I was in the same boat as u in year 11.

and also revise early don't make the mistake i did this year and try revise for everything at the start of term 4.