This is where creating a legal fiction gets you, to a place where 2 men, with 2 bits of paper can be lesbians. The same two men, without the bits of paper, are gay men. The article lays this madness out I think better than anything I have seen.
I am not sure what the best outcome is here. That GRCs do not qualify men to use all women's services and spaces, or that the law is, a man with a GRC is a woman for all intents and purposes but this is clearly bonkers and we need to go back and change the legislation so that is doesn't create this madness.