https://www.mumsnet.com/talk/womens_rights/5556178-trans-guidance-for-civil-servants-must-stay-secret-ministers-say?reply=153626224&utm_campaign=reply&utm_medium=share
According to a PP on another thread:
"The guidance is to ask people to use toilets and spaces appropriate for biological sex but they will not actively enforce it, as they say it isn’t possible. They have also reinforced the guidance that says it’s a disciplinary offence to deliberately call someone by the wrong pronouns etc."
I am more worried about the first sentence than the second. Clearly, correct toilet and changing room usage can be enforced via normal disciplinary procedures, and it's nonsense to suggest otherwise. Employers know what sex their employees are, and, in any case, Schedule 3 permits exclusion of anyone who looks as if they are the wrong sex, whether they are or not. No need for genital inspections or original birth certificates!
It seems like they're going to operate a don't ask don't tell policy. Employees should complain to the H&SE.
As for the misgendering business, if we lived in an otherwise sane world, I could imagine employers not unreasonably asking employees to mis-sex their trans colleagues as a courtesy, to accommodate their niche beliefs and lifestyle (as one might for other minority religionists). We don't live in that sane world yet, though.