I cannot wait to leave highschool and go to University.
I don't know your situation and it may very well suck but once you get to uni, you'd be surprised how many people would want to reverse this direction (maybe even myself a little). Cherish it, if it's absolutely horrible, then, make the best out of a bad situation.
I'm hoping to undertake a Bachelor in Biomedicine or a Bachelor in Science
My main problem is that for each University I've looked at, the minimum ATAR is in the high 90s.
Most science courses are not 90. I know Monash is around 80, melbourne is somewhere around 88 i think and it all drops off a fair bit after that. So, i wouldn't worry too much. All uni's teach basically the same thing in undergrad. It's not like you'll massively miss out if you go to La Trobe Vs Monash. Even then, you can transfer if need be.
I got no tips except the obvious, work hard. People can give you all kinds of fancy and flashy advice but in the end, it really just does boil down to this. In VCE and in life in general, it doesn't matter to the extreme how smart or capable you are at x, its if you actually work towards x. I've seen many people who are incredibly intelligent do almost no work in uni and totally drop the ball. If you handed in no work but say "Oh, lecturer, i'm so intelligent though", you're still getting a 0. If you're in the workplace and do nothing but say "No, really, it's ok, i'm a genius" you won't have a job very long. In the end it all boils down to action over inaction.
If you don't get where you want uni is very flexible. There are pathways to transfer around and its a lot less rigid and structured than school.