Datun
What you need to understand - and I know there are a gazillion things all going on at once! - is that AWS are different to anything else. In the normal run of things, AWS would be illegal on the grounds they discriminate against men. But, EA2010 made a very specific exemption in the case of AWS only because female representation in politics was so woeful.
*The AWS exemption is for a limited time period only - up to 2030.
*It allows for AWS on the protected characteristic of sex.
*A GRC changes legal sex so women and GRC holding TW are eligible.
*After 2030, the limited time for improving female political representation will be over and there will be no more AWS.
AWS in this context relates to prospective parliamentary candidates only*. All women shortlists for other things are not covered by this exemption.
*It is currently illegal to allow self-ID in AWS for this reason. But self-ID in other areas depends upon entities invoking the other, more general, single sex exemptions in EA2010. Two different things.
*This is a completely separate issue and has no bearing on self-ID in other areas or on other single sex exemptions in EA2010.
Hope that helps!