Life, education,monney

Hi iam really stuck at the moment, life seems to be getting more defucult everyday. I WANT TO devlope, but I don't know how, I want to make money to help my family, but I DONT KNOW how. I am still fighting my way through A levels, trying my best to get the best grade that I can. which in some way seems like grade A or B impossible, but I will still fight.
My aim is to go into diagnostic radiogrophy.
I really want to work and start making money so that I can make someone out of myself, but I don't know how. I have a motability problem. I am not saying this means I can't work, but it is just limiting the things I can do
So the only way I could work is by me being sat down or I could work in a place where it doesn't need much walking around.
What would would you recommend me doing
I am 18 years old