The Department for Education states that:
You must make sure your child gets a full-time education that meets their needs (eg if they have special educational needs). You can send your child to school or educate them yourself. Children must get an education between the school term after their 5th birthday and the last Friday in June in the school year they turn 16. If your child is unexpectedly missing from school and the local council thinks you’re not giving them home education, you’ll be contacted by the school or the council’s educational welfare officer. They’ll contact you even if your child is only missing for a day. You can be prosecuted if you don’t give your child an education. You’ll normally get warnings and offers of help from the local council first.
You can only allow your child to miss school if either:
There’s extra support available if your child can’t go to school for long periods because of a health problem.
You have to get permission from the headteacher if you want to take your child out of school during term time.
You can only do this if:
It’s up to the headteacher how many days your child can be away from school if leave is granted.