I would send it to the designated safeguarding lead with the Head on copy.
To keep it non-confrontational (this is key IMO but others may feel differently), maybe something like:
"I'm aware that there have been several developments recently in both health and education (started under the previous government and continued under this one) relating to gender questioning children. Specifically in education, there is growing recognition that not everyone believes that we all have a gender identity and that the children who do (and feel that theirs differs from their sex) may be at a wider safeguarding risk where their distress is conflated with autism, an emerging same-sex attraction or other factors. Following the release of the new statutory KCSIE guidance (in particular paragraphs 205 to 209), please can you advise how the school will be updating the [name of policy] policy, where is currently states: [paste in policy wording]"
Edited to include "an emerging same-sex attraction". In my experience from talking to a school, the conflation of LGB and T is very deep-rooted. Many people who conflate the two do so from a well-meaning, supportive place. It's easy to see why they would, given we're constantly told that LGBT is one "thing" and that to say otherwise is "homophobic" and/or "transphobic".