Incidentally, looking at the preview of the trans guidance, it appears that people who are disappointed by how weak it is need to consider the application of the law.
It appears to accept that gender reassignment is a protected characteristic for children.
It also appears to stick to the Equality Act on single sex spaces. The prohibition on participation in contact or competitive sport of the opposite sex still leaves the option for participating in PE or non-contact, non-competitive sport with the opposite sex. Proportionate means to achieve a legitimate aim.
Those who want it strengthened perhaps need to be looking at what is legally possible. I suspect that they have already done that though.