The EHRC are giving guidance based on the minimum that all parties agreed in FWS - that we do not have self-ID. The guidance says that and that providers must not operate as if Self-ID was the law. They also put paid to the ideas that access to SS spaces should be decided case-by-case and that anyone with a trans identity ought to be granted access to facilities which accord with their GI except in exceptional circumstances, neither of which ever had any basis in the EA2010. It's basically correcting the errors of the TA-influenced statutory guidance of 2011.
The question of whether MCWs with a GRC can join women-only gyms, lesbian groups etc is what will be decided on Wednesday. If I understand correctly, regardless of the SC judgement, women's RCCs and communal changing rooms etc can still be off limits to males with a GRC.