Yeah - 18 to buy drinks (though at the age of 17/16 you can normally get away with it), and 12 at home or at a party, aslong as you have the houseowners permission to do so.
There used to be a law that you could drink in a pub at 16, aslong as you had a guardian with you at all times and buying the alcohol.
well im tall for my age (every bit of6' 2"), ive finished school so that gives u an estimate to go on. neway when i turned 18 i was legal to buy and drink alcohol (which is how it is here) but u can drink at mates places n stuff provided that its not too rowdy and the neighbours dont call the cops or what ever. so pretty much provided that u dont draw attention u can do it easy enough. but yeah ppl do get caught for it.
when i turned 18 and first went to buy some Bundaberg Rum (THE ONLY RUM FOR AUSSIES!!!!!!!!!) i was expecting to have to show ID but the damned lady never asked for any... i felt so deflated!!! then i realised that i coulda been buying booze AGES before i was 18 cuz im tall and look 18 for sure!