It's still a bit vague and non specific
To be protected from gender reassignment discrimination, you do not need to have undergone any specific treatment or surgery to change from your birth sex to your preferred gender. This is because changing your physiological or other gender attributes is a personal process rather than a medical one.
You can be at any stage in the transition process – from proposing to reassign your gender, to undergoing a process to reassign your gender, or having completed it.
I mean anyone can say they are proposing to change their gender yet not ever do anything concrete about it whatsoever never mind have surgery or apply for a GRA.
They then go on to say
a service provider provides single-sex services. If you are accessing a service provided for men-only or women-only, the organisation providing it should treat you according to your acquired gender. In very restricted circumstances it is lawful for an organisation to provide a different service or to refuse the service to someone who is undergoing or has undergone gender reassignment
Which feeds back into you can just say you are proposing to change gender and access any service as a 'thinking about it' person.
On sports
competitive sports: a sports organisation restricts participation because of gender reassignment. For example, the organisers of a women’s triathlon event decide to exclude a trans woman. They think her strength gives her an unfair advantage. However, the organisers would need to be able to show this was the only way it could make the event fair for everyone
Does being able to show this include statements like 'well duh of course males are faster and stronger than females?'