I sent my DS primary school Head the guidance using this link.
sex-matters.org/take-action/send-guidance-to-school/
I complained last year after PHSE lesson contained the 'born in the wrong body' explanation along with the caveat that kids could only change if they really really believe they were born in the wrong body. This was year 4.
I complained as a disabled parent who can't opt out of my body, and also because I experienced traumatic puberty. I started my periods age 8, was neglected by my mum and never given sanitary towels, I had to make do myself until I started high school. I was also sexually abused and that started when I was 9, having already grown breasts and was wearing a B cup bra. I would have opted out of my female body in a heartbeat if it were possible. I'm so glad I didn't know it was possible to halt puberty, to stop periods, have my breasts removed and hide my female body by becoming a trans boy. I know 100% I would have gone down that route.
I received a reply from the Head Teacher which I'll add in a separate post.