The first thing you have to do is to raise your concern with the headteacher of the school concerned who will investigate your complaint. You will find contact and location details for all schools in the borough in our school finder.
If you are dissatisfied with the outcome of the headteacher's investigation, you should contact the chair of governors. The school will tell you how to do this.
If you are not satisfied with the response from the Chair of Governors, you should address your concerns to the Department of Education, who have the power to investigate your concerns further.