I'm the same, most decent people accept (after a few rebuttals maybe) that you don't drink and won't think any less of you, I've found. Just don't be one of those people who looks down on people that do drink, because that will annoy people.
From what I've seen on the freshers pack I got today, there's some pretty good 'drinker' events that you could probably enjoy if you didn't drink. Even if the worst comes to the worst and you hate freshers week, it usually calms down after that from what I've heard.
Most of my college mates drank a lot and the worst they did was tease me at times about it, just get to know people and act chill towards them, and you'll be fine. Hope to see you there, what halls are you in?