It's kind of hard to not at least have a vague idea of how to sing God Save The Queen, I mean you're only expected to sing the first two verses at most anyway. We don't sing it much, I went to a proper Christian primary school, the school was literally next door to a church and I never want to sing anything ever again. Two or three hymns every morning from the entire school, I learned to hate the one about all of god's creatures cuz it never ended. The teachers were constantly on their shit for anyone just pretending to sing or just keeping their head down too, you were not getting out of it.
I was shocked when I got to secondary school and just flat out was not expected to sing anything for the entire 5 school years, nevermind having to go down the road to church once a month.
I'm not even religious despite it all as well, even then I was waiting for the pin to drop and the teachers to go "this is all metaphorical, just be a decent fucking human being ok?" What's the religion where you don't exactly believe in God but you like Christianity as a way of thinking? I know it has a name, I suppose i'm one of those.