Can I go camping in the United Kingdom at my age with friends?

Okay my friends and I have planned on going camping this weekend, We are 15 there is going to be like 6 of us going. Everyone in my school has been camping with other friends before besides me and every time the next day they go on about how much fun it is, so I asked my mother today and she said No, because we are under-age. But my friends say it's 15, we don't do anything illegal we are not that type of people suprisingly but my mum started having a go at me saying their parents should be arrested and she wouldn't do it if she loved me and it's tough ****. but I personally think it's because I'm the youngest of my 3 other siblings so she's finding it hard to let go on me. Is there any proof that it is 15 or is there any possible ways to convince her to loosen up a bit and allow me on this camping trip.