It's harder, practically, to enforce civil rights than criminal law. And it's not a given that a TW in a changing room is inherently committing voyeurism/indecent exposure, so I dont see the CPS taking an interest except in the most egregious of cases. In any case the TW doesn't even have to exist: it's the policy that creates the problem, by making women unwilling or unable to use the CR, once they realise men are allowed in.
I feel that the real problem right now is that the institutions are against us. As pointed out in the Darlington judgment, there are laws mandating single-sex provision on pain of criminal sanction, such as the Workplace Regulations (but also laws about prisons and schools). People could get fined, at least.
Yet, the institutions (eg ScotGov) are straining every sinew to continue to break these laws, as well as to ignore FWS by endorsing discriminatory practices, punishing anyone who complains, and hiding what is going on under weaselly language.
Southwark Council should be protecting all its residents' rights under EA2010. At the very least they should require their gyms to put up signs saying 'this is the women's changing room, but any man who wishes to use it may also do so'.
How did the institutions get so captured, when surveys tell us that fewer than 20% believe in this nonsense?