Honestly, it all depends on the people you meet. I was unlucky enough to end up in a flat with people who wanted to go out binge drinking every single night of freshers, and we never ended up becoming friends because I'm such a quiet and introverted person and they're all so extroverted. In fact it's been very awkward living with them, so my situation has been kind of the worst case scenario for me!
However, you will make friends with people on your course. They're much more likely to have similar interests to you. I met my current friends at uni through someone on my course, so even for someone in my bad position, you can make friends by doing things other than getting smashed all the time.
You can try to go out a couple of nights in freshers week just to try it and see if you enjoy it or not, but please don't force yourself to drink loads if you don't enjoy it, it's really not for everyone and as you get older you'll meet many more people who don't drink all the time. I won't lie to you though, at this age, most socialising seems to be done through drinking.
You will meet friends though, as long as you try to come off as friendly as possible in the first few weeks of uni, and don't be afraid to talk to people you don't know. Most people are strangers to each other here and will be glad to talk to someone friendly!