Am now on a proper computer and so can type properly.
This is also a very helpful summary and was I think written before the Cass Report which would support what it says strongly:
https://safeschoolsallianceuk.net/wp-content/uploads/2021/08/22Aug_Advice-note-schools-socially-transitioning.pdf
Questioning your gender is a natural part of adolescence for many teenagers and it is not for the school to judge whether this is because they are trans, because they are a teenager or whether there are other factors at play such as neurodiversity or abuse.
Over the last year, it has become increasingly clear that schools who transition behind parents' backs are on very dodgy legal ground, but there hasn't been a case because, frankly, who would want a court case when you've got all this on your plate as it is and an unhappy child. (I say that as someone who has been there and got the t-shirt, and Safe Schools Alliance would I think have supported us had we done a court case.)
But again, remember that you don't have to say anything yourself today. Ask questions, write the answers down very carefully and say at the end that you are going to be taking advice from other sources. Then email them a summary of the meeting afterwards.
Then, when you know what they are saying talk to Transgender Trend, Bayswater (who helped us so much) and Safe Schools Alliance. They will give you very specific advice and support.
Also, look at @ROGDmum who is on here and on Twitter (https://twitter.com/rogdmum) who has been battling this for 3 years - her recent threads on what happened are shocking.
Good luck, will be rooting for you.