I think it's a mistake to think that schools guidance can be what puts the kybosh on all of this.
It's one piece of the puzzle, but there are limits to what it can do and there always will be. The same principle that says that schools can't change kids names without parental permission, also says that parents are the final arbiters of appropriate medical interventions, along with doctors.
So as long as there are doctors spouting gender ideology, and parents, it's not going to be schools that stop that from happening, It's just not their role. To try and undermine parents would just be another
That's going to limit the degree to which they can say they will never allow kids to transition in school.
What should be happening is that schools stop hiding stuff from parents, promoting GI or queer theory in the school itself, and focus on safeguarding elements that are really part of their remit - rules for sports, rules for toilets, and rules for the degree to which other kids need to "respect" kids who change names etc.
Stopping medical and social transition of kids is going to require changing the medical side of things, and the ideology, directly.