Under 18s:

Adults are not allowed to buy alcohol on behalf of under 18's in a licensed premises. In the new licensing laws, the only exception is for 16 or 17 year olds who are allowed to drink beer, wine or cider at a meal out with adults (but they may not buy the alcohol themselves).

It is legal for anyone over 5 to drink alcohol. The restrictions apply to purchasing (under 18) and location - on licensed premises or in alcohol exclusion zones. Police have powers to confiscate alcohol from under 18's drinking in public spaces (e.g. in the street or in parks).