Glorianny, do you have insider knowledge of the Tavistock? If not, how do you know what they have advocated? It may be that surgery is not performed on under 18s, but that does not stop it being advocated - in fact, my understanding is that it often is, along with the affirmation that they definitely advocate.
I don't, whatever you may think, want children to suffer, and I do believe that many are suffering as a result of whatever it is that is making so many of them question their sex. I don't believe in so-called 'gender', but I do think that if people wish to live according to norms more usually associated with the opposite sex they should be able to do so. We were, IMO, moving along that road anyway, but then we were told that the only way to step away from the gender norms of our sex was to become the other sex, with no understanding (or, as far as I can see attempts to understand) of any of it means. What is a woman/man? What does it mean to 'feel like a woman/man'? How do you know? All of those things are called 'leading questions' and get ignored, and that's without the utter nonsense of believing that people can go against Nature and change sex. If those questions could be answered, and we could believe that children were asking for something that (a) made sense, and (b) was possible, I might feel differently.