It's so hard OP.
I am in Scotland, sent my kids to a non denominatiobnal school, there was a lot pf religious indoctrionation, in assemblies ( local minister often preaching) but also in class, bible stories, prayer, chat about Jesus etc.
Kids were taken to church seberal times a year for worship.
And yjis was a " non faith " school. ( Although I understand there is no such thing in the UK)
I became a parent helper, I became a school governor, the head was not to be moved in the amount of christian indotrination he chose to deliver.
He was within his rights, in fat had a legal requiement to deliver worship ( which he does).
I did think about removing mu hildren from assembly, but didn't for several reasons.
Instead I worked on removing and "progamming" at home.
Happy to say they remained atheists ( as they were born) for theit childhood. But is was not easy.