Once you have made friends they should be fine with it.
You could just drink small glasses of coca-cola, people won't be able to distinguish it by looking from vodka/rum/whisky and coke.
Not smoking shouldn't be a problem, nor should not doing drugs, since they are not really "expected" behaviour like drinking is, and even with drinking there are plenty of people who don't drink, and even more who drink just a small amount.
I don't like to get really drunk, although I do drink. I will sometimes drink on a few nights out in a row, sometimes I won't drink for over a month, people just accept that I am not drinking at the time.
I don't smoke unless I am drunk, which happens by accident now and then if I am particularly tired, or haven't eaten properly and I drink a bit too fast.
I don't really take any drugs. I use cannabis now and then, more in the past, but if I am with friends who are smoking it they are happy to let me be a part of the situation without smoking anything.