https://www.gov.uk/child-study-visa/overview
What you can and can’t do
You can:
study at an independent school
apply from outside the UK
apply to extend your stay
You can also work, if you’re 16 or over:
part-time during term for up to 10 hours per week
full-time during vacations
on a work placement as part of your course, (but not for more than 50% of your course time)
as a student union sabbatical officer for up to 2 years
You can’t:
study at an academy or a local authority-funded school (also known as a maintained school) or further education college
get public funds
take a full-time permanent job or be self-employed
work as a doctor or dentist in training
work as a professional sportsperson (eg a sports coach) or entertainer
settle in the UK on this visa
bring in family members (‘dependants’) - if your parents want to accompany you, they’ll need to apply for a Parent of a Tier 4 (Child) visa