The EHRC have opened up a consultation which runs till January 2025 on their updated code of practice in line with changes or clarifications of law since the original was written.
https://www.equalityhumanrights.com/media-centre/news/equality-regulator-opens-consultation-updated-code-practice
It’s a long read and to be honest if I was an employer I would still struggle to interpret some parts.
Below is some information on Gender Reassignment discrimination focussed on people who identify as NB, Genderfluid or cross dress. My interpretation is that these come under GR on the proviso that the individual’s ultimate aim is to reassign their legal sex. I’ve seen discussion on something similar re the LandRover case. I’m not sure how this works for an employer. Would a person have to declare that this is their aim to be covered? It’s often been inferred that someone identifies as NB is doing so because they don’t want to identify as any gender (often interpreted as sex) not a need to reassign their sex. Would they not be covered? It’s all confusing.