Alcohol is a social lubricant which, yes, we shouldn't rely upon. But there are a great many things we should do that we don't - I don't see alcohol as a huge problem in that regard (unless, you know, it becomes a huge problem for you personally).

I also have friends who don't drink, including some when I was at university (a high time for most people's blood alcohol levels) - few people cared. Though my one suggestion to you is to drink something other than water, even if it's just club soda. Aside from anything else, getting something that costs money will likely make the pub staff friendlier.