Drinking laws in England

I’m currently enjoying the British show Inbetweeners. In it, the teenagers seem to engage in quite a bit of sanctioned drinking, including at school events where they could each have 2 beers. What are the laws for younger people drinking in England? How does that work? (I’m trying to figure whether I would’ve drunk more or less if it were legal. I’m guessing somewhat more.)

I know US is prudish about such things, but what are the laws/practices in other countries?

“All four of you?”
(punchline suggested by duplicate thread)