The Department of Education recommends that every child in a state school (primary and senior) gets around one to one-and-a-half hours of religious education each week. This is only a guideline but most schools do adhere to it. Sometimes the teaching itself deals with ‘moral and spiritual issues’ rather than specific religions. Many senior schools drop RE from the curriculum at around 14/15 years unless it’s part of an exam syllabus.
Most schools teach a variety of religions in RE to give children a comprehensive understanding, although some schools will put more emphasis on Christianity.
If your child attends a church or other religious school the emphasis on religion will probably be stronger. Some Catholic schools, for example, have a religious assembly every morning plus one or two separate lessons of RE every week. Normally, other religions will be touched on too. Each individual school will be different, so talk to someone at the one you’re concerned with if you want to know more.