The Times has seen a copy of EHRC's final guidance

[Igneococcus]

and it looks like it's pretty rubbish:
"Under the new guidance, places such as hospital wards, gyms and leisure centres will be able to question transgender women over whether they should be using single-sex services based on how they look, their behaviour or concerns raised by others."

https://www.thetimes.com/article/82eecc43-711f-4c0a-b669-42d09d60d63e?shareToken=e5c7b92df4468caa07dbd71d66c660ab

Exactly. Take this to its logical conclusion and employers might choose to get rid of pregnant women who had changed their legal sex to male, on the grounds they knew pregnancy was not a protected characteristic for that group.

There are so many problems created by introducing the falsehood that sex can be changed into the law.