I'm not sure that it is unlawful. Fucking awful, yes, but unlawful, not so sure.
The EqA is one of the greatest sleight's of hand ever perpetrated on women. You might think that it would be illegal to turn single sex spaces into mixed sex spaces but you would be wrong. The provision of single sex spaces, where that provision would be lawful under the EqA, is discretionary rather than mandatory. If the provider chooses not to provide a single sex space then that is lawful. Daft I know but that's where we are.
If a colleague changes their name for any reason and you persistently use their old name despite being asked repeatedly not to, you would be harassing them and an employer could discipline you.
The bit that I think could be overreach is pronouns. You don't own your pronouns in the same way that you own your name and choice of pronouns is up to the speaker/writer. I would guess that trying to enforce specific pronoun usage is coercion and illegal.
Please be aware that I am not a lawyer, I just spend a lot of time picking holes in contracts.