It is important that we distinguish clearly between religious studies, as in a subject, and religious observance, where a deity is being revered and prayed to.
If religious studies is to be taught as a subject, then the subject matter should be compiled by the Department of Education, and should fairly cover the significant religions, what their history and tenets are, etc. It is not the task of school governing bodies to formulate curriculum.
Ideally, religious observance should not occur at government schools whatsoever. As a compromise one might consider allowing religious observance at the school, but not during school hours. The pupils who wish to partake, can then come to school a bit earlier or stay a bit later. That should quickly establish how serious they are about it.
My thoughts, my beliefs, my feelings are all in my brain. My brain is going to rot. - Richard Dawkins