It depends on the school, unfortunately. When I was Year 11, my school had compulsory revision sessions at lunch, after school AND no study leave. We used to have it but they stopped as not everyone uses it productively. While you can't deny that fact, it was a pain in the ass as we had to go to lessons for our subecrs even after all the content had been covered. THEN they made us go to revision sessions for our remaining exams in free slots so we couldn't have any frees in between. We had to go to school right up until our last exam... -_-
Mind you, we still had a glorious 11 weeks of holiday after all that so it was worth it. Still annoying that we weren't given a choice to have study leave though, considering most schools have it.