Just for information, and this might not be exact because I don't have the documents in front of me, being on maternity leave, there is quite a strict criteria of getting into a Catholic school.
The first children taken in are 'cared for' children, kids who are in state care and fostered, etc. It is not particularly important, I don't think, which religion they are. These children need as much care and positive imput as possible and Catholic schools recognise their responsibility here.
Secondly, children who live in the parish catchment area and have been baptised and are - and their siblings - are next on the list. I don't think you have to go to Mass regularly to qulaify here, but I've no doubt it would go in your favour.
Thirdly, I think, correct me if you know better, baptised Catholics who apply from other parishes get in and then non-Catholic Christians from the local area and then children of other religions.
Catholic schools are not state schools, but pay the state to have the privilege of having a school which is founded on and tries to live out the beliefs of the faith and this is why they are usually very good schools because they offer something above and beyond basic education.
No religion is perfect, as they as all man-made, but, frankly, it pisses me off when people comment so forthrightly on how its a loads of 'mumbo jumbo' and then try to get the benefits whilst ignorantly slagging the religion off.
It would be nice, in an ideal world, if people had a bit of respect for or sensitivity towards those of us who are just little people trying to live our lives in a way we think is best instead of being arrogant and thinking that they have it all right and we're stupid.
But hey, that would be an ideal world.