If you are defining it as saying you are under going gender reassignment and no medical supervision is needed, then that's already happened.
I never realised this - I never read this key bit.
www.gov.uk/guidance/equality-act-2010-guidance
Equality Act provisions which came into force on 1 October 2010
changing the definition of gender reassignment, by removing the requirement for medical supervision
Which basically means you don't need any medical supervision to say you are protected under gender reassignment as a protected characteristic.
Isn't that self ID?