They shouldn't need to be - else no non-christian religion would be able to attend. Yes, they do need to give a percentage of places to kids outside of that religion to maintain government funding.

Having said that though, you would have to be prepared for the kids to receive religious Ed at the school - having survived a full catholic education, I can honestly say it's the only reason I have any idea of a broad range of religions - our school had senior assignments in other Christian *and* non-christian religions. So it was very good for a brad religious education. And also in learning to appreciate beautiful music in the way of hymns.

Good luck! And definately contact the school and ask these questions.