The Education (Pupil Registration (England) (Amendment) Regulations 2013 state that Headteachers should not grant approval for any leave of absence during term time, including holidays, unless there are exceptional circumstances.
These regulations also state that holidays cannot be authorised retrospectively. Any requests should be on an official school absence request form and handed into the school office for consideration prior to any holiday/leave arrangements being made.
You may be issued with a Penalty Notice should leave be taken which is not authorised. If unpaid this could lead to prosecution under section 444(1) of The Education Act 1996.