A complaint about a school should, in the first instance, be addressed directly to the particular school it is about. If you are not satisfied with the school’s response to the complaint you can appeal to the school's Chair of Governors.

In the event that you are not satisfied with the Chair of Governor’s response, you can ask the governing body to review it. This request would need to be made in writing within fourteen days of the Chair’s response to you. The governing body’s complaints committee will meet within twenty one days of receipt of the request to review the details of the complaint and the evidence provided. The chair of the committee will send you a letter within five days of the meeting notifying you of the outcome of the review.

For more information please visit Complain about a school - Gov.UK