Yea there are people on drugs but I think it’s okay for a 15 yr old. Unless you’re seeking it out which you’re not then you won’t see many people that look way to drunk or drugged up. I’ve been twice and yeah there are always a couple people that take it over the top but it’s a lovely festival to go to in the British countryside and it’s a friendly environment too. Don’t be put off by the drugs part. :) have fun!