I did this cooking competition in year 8 in which I placed third (but only the top 2 went onto a county-wide competition

)... knew I used too much salt
Otherwise our school had house competitions and I remember taking part in Chess and a Quiz team. Wasn't amazing at either, though. In terms of sports it was mostly just swimming clubs... we had to do house football, house rugby, house athletics, etc, but I was tragic at all of them
Not-school related, I did karate.
I really wish I'd learned a musical instrument.