This is from the GRA consultation:
113 The Equality Act enables separate or differing services to males and females, or to one sex only subject to certain criteria. These services can treat the people with the protected characteristic of gender reassignment differently, or exclude them completely, but only where the action taken is a proportionate means of achieving a legitimate aim
114 As an example, refusing a transwoman with or without a GRC access to a female toilet in a pub is likely to be unlawful, but a female only domestic violence refuge may provide a separate service to a transwoman only if it can be shown that there is detriment to other service users from including the transwoman as part of the regular service.
This seems to say that anyone calling themselves a woman is entitled to be in women's spaces.