Second this:
In my country you are allowed to drink beer, wine, champagne and similar light stuff at 16, liquor at 18. As a teenager I was a member of two different youth groups. : A catholic group at Frankfurt Cathedral, and a group at our Ambulance Service (Similar to Youth Red Cross). In the Catholic group beer was allowed, we had two fridges with about seven different brands of beer, Coke, Sprite, etc. People who liked a beer simply had one - no taboo (As long as you were at least 16). Everybody took care of each other and learned to handle the stuff.
The other group at the Ambulance Service was strictly 'dry'.
Both groups did field trips over a weekend every other month. In the Catholic group we never had problems on those trips, because it was nothing special for the people to have a beer - or two
With the other group we always had wild parties with heavy drinking, because it was something special to be abroad and be allowed to drink.
IMHO by prohibiting something strictly, you only make it interesting.