Icelandic Drinking Law

I'm visiting Iceland in the summer with a friend (18 and 19) and we were wondering how strictly enforced drinking laws are there. From what I've heard from other (better-travelled) people, here in England we've some of the most strictly enforced laws in Europe, but I've been served in a variety of places since I was 16, and I'm hoping that I haven't lost the two-year headstart and I'll be able to enjoy a few brennivins and beers even though the age is 20.

I went to Iceland briefly a few months ago (hence the longer trip now; how could you not want to go back?!) and I think I had a beer in a restaurant (I can't remember, but I wouldn't have thought much of it because I assumed it had a laxly-enforced age of 18 like most other nordic countries - I had more than a few beers in Denmark about a year ago, no questions asked) but I was with family for a meal so they may have bent the rules.

We're not looking to go for the nightlife, and we're going to Denmark and the Faroes first, so we can get our fill there if needs be, but we just want to know whether we'll have to bring our own drinks for our midnight sun-downers or if we'll be able to go an ATVR and pick something up. Thanks!