When you apply for school places, you list the schools you prefer in order of preference. We get to list 3 schools in my area.
All children applying are ranked according to selection criteria.
For non-denominational schools these are typically (1) children in care; (2) children who have a sibling at the school (3) all other children in order of distance they live from the school. If you live in an area with formal catchment areas, children in catchment will typically rank above children out of catchment .
For religious schools, children of the "right" faith usually rank higher than children of a different faith. E.g. our nearest religious school (Catholic) ranks children in order of (1) Catholic children; (2) Children from other recognised Christian faiths, (3) Children from other faiths; (4) Children of no faith. Children within each group are ranked in order of children in care -> siblings -> all others by distance. So if you don't list a faith on your application form, you're likely to be pretty far down the list for getting in a religious school.
Once all the school applications have been looked at, if your DD is within the number cut-offs for any of your preferred schools, she'll get offered a place. E.g. if she'd be eligible for preferred school 1, preferred school 2 and preferred school 3, she'd get offered a place at preferred school 1. If she'd be eligible for preferred school 2 and preferred school 3, she'd get offered a place at preferred school 2.
If all your preferred schools are oversubscribed to the point where your DD doesn't make the class number cut-off for any of them, then she'll get offered a place at the nearest school with places remaining. If this nearest school is a religious school, then they'll offer her a place there, regardless of her religion.