Seriously, don't let VCE rule your life.
When you look back you'll be looking back at all the "haha... remember when X did this!" not "omgosh i studied so hardcore all weekend and got 98% on my chemistry exam!"
I agree with jane1234. Kyzoo having gone through year 12 and myself also going through year 12 also seem to reach the same conclusion.
Really guys, take it from people who have been there (like me!). You work it out to be some big bubble or the absolute be all and end all of everything. It really isn't. You aren't a bad student if you go out with your friends on the odd occasion, you really aren't. Unless its the day before the sac or anything like that, going out on the odd occasion really wont affect your mark much at all :/. It really won't....
These are some of the best years of your life and i'm not just saying that. I had a really awesome group of friends, year 12 was probably the best year of my life friendship wise and social wise, it really was.
I'll share a little story. On the last day of official classes my largeish group of friends and I went down to the local shopping centre to sit down in a place and all eat together. The (youngish 19-20 at most, i think she finished highschool the year before) waitress realised it was our last day and we were all in uniform, she told us "Really guys, enjoy it while it lasts. I know it doesn't seem like it now but you really will miss it and all your friends. I know i did" or something akin to that. I thought i understood what she meant at the time but i really didn't.
Looking back and having half a year of uni under my belt, i truly realise what she meant now. Most of my friends are all over the place at different unis and doing different things... i see them once every couple months really. You think "Oh, definetly we'll stay in touch

!" "We'll see each other every other week" and things like that, bad news guys, things from what Ive seen hardly ever turn out to be like that. Unless of course you all wind up at the same uni but i've pretty much got no one from my old highschool group here at monash.
Really, now should be one of the best years of your life, grab it and have fun with it while you still can. Eventually you group will slowly disappear around you...people get married get jobs...different uni...ect. It'll be much more worth while to you than the extra 0.05 ATAR points. So, really guys, don't totally ditch your social life thinking it'll make you an epic student or give you an epic score. It isn't worth it at all.