You should go to school, and leave the house. If not, you want to grow up and be treated like an adult right? Well adults have responsibilities, so get a job and pay rent, and help out with food. Real talk.
Do you actually supposed to leave your mother at the age of 18?
If your mother doesn't mind you living there then you're cool to stay. In England you are legally allowed to move out even if she does not want you to. But if you have a full time job it may be a nice idea to be a bit of rent a month to your mother for food, electricity, water etc.