you have to go through KYC verification there. it might be a bit troublesome if you don't have any documents yet.
P2P is currently the most recommended for you. Bitcoin asset ownership is not affected by age. the most important thing is that you already have the awareness to be responsible by carefully storing your wallet where you store your assets.

you have a good idea by allocating some money to Bitcoin. By doing it consistently, you will get extraordinary benefits in the future. you have started it well, hopefully, everything you do will run smoothly. if you have any difficulties, don't hesitate to ask in the forum.