"Does someone having a GRC certificate mean they can access single sex spaces including women's prisons despite the Equality Act single sex exemptions?"
Correct, Namechanging.
Male people with a GRC are usually automatically put into a women's prison. Lauren Jeska who attacked Ralph Knibbs was automatically sent to a women's prison.
There are a small number of male prisoners with a GRC who are held on a transgender wing of a women's prison. This is because they are deemed to be a risk to women.
I believe that there are some male people with a GRC who are still in the male estate. Because they are deemed completely unsuitable for a women's prison. No shit.
As I said previously, they are treating these male people with a GRC in 3 different ways so I suspect that lawsuits for discrimination are in progress by those inmates who are in the male estate, or in the transgender wing of the female estate. The MoJ are effectively saying that some males are definitely women, some are nearly women, and some are not women at all.
See also Karen White who does not have a GRC. White was put in a women's prison. The transgender review panel were not aware of White's offences committed under another name as a man.
You'd think that the MoJ would invoke the single-sex exemption. Say no males in the women's estate ever.
And then address the issue of male transgender people separately.