I don't think age is too important, it just depends what you're into. If you want to apply to rootes then go for it. Bear in mind the type of hall it is (lots of drinking and staying up late and having parties if my information sources do not lie) and if that's your sort of thing then apply there. It's sort of mine, I just hate tidying up so I applied to Whitefields cos its close to the union so when I'm pissed bed isn't far away but means that I don't have to clear up in the morning (the noise wont matter, I sleep anywhere). But most people (probably everyone) started drinking before they were 18 and a uni ID seems like a really useful thing if you're underage actually (that sounds bad, but its true), cos I don't drive and don't like carrying my passport around so that's what I plan to use (although I don't get ID'd much anymore, it's always useful to have).