Definitely comes down to the exams for you, Sam! You're in a good position as far as your SACs go - it's not as if you've been failing all year - so it's definitely achievable from here. As for "how hard is it to get an 80+" - it's fairly difficult but by no means implausible with some hard word. You should be able to get 80+ - but NOT based on your average grades - just based on what you can do between now and the exams and how you can perform in the exams. Let the 'freak out' feeling motivate you to work as hard as you can. Think of it like... "You will get an 80 ATAR if you can run a 100m sprint in 15 seconds". There's a track, 80+ ATAR at the end. If you jog, you'll fall short, guaranteed. If you sprint, it's only natural to make the 100m comfortable within the 15seconds (lets just asssume our runner has been jogging for the past year). So, it all depends on how had you go down the track. Walk, jog, run, sprint - some are going to yield different results, but one is going to give you an excellent chance.