I start investing loads of money. I am planning on putting £10 every month into bitcoin.
Also is it even legal for an under 18 year old to invest in bitcoin.
I have already invested £20 which is now worth £40.
I must commend you for your investments at a very young age, if you are still doing it till now well done buddy for going into the investment route. However, I've got to advice you to slow it down a bit because as an adult teenager investing in Bitcoin can be tricky. While Investing in Bitcoin you need to know that Bitcoin's value is likely to go up and down and you could win or loose your money so be careful and guarded.
Slow down ? I'm a few years old than @OP and I have been investing in bitcoin since I knew about it perhaps it's even best to be more aggressive now than ever in my opinion. I haven't learnt a lot how life could be when one starts taking responsibilities especially family responsibility then attentions get divided and discretionary income becomes very low but at his age (including me) we have a very good discretionary income because almost all our savings or income is just for our personal use which are mostly nonsense we spend on but since I'm quite opportune to be here I put those money in to bitcoin and in future I know it will worth it all.
All you have to do is encourage @OP to be careful with coin security and be at his best security wise while holding his bitcoin and also clear his mind from thinking of bitcoin to be a get rich quick scheme instead he should consider all that little money he puts there to be returned after 4 years plus or a cycle before he can think of his profit if not he will probably be in regret or loss if he wants to buy bitcoin for just to get profit in less than few years.