Any male looking person in the ladies will rightfully be challenged both now and after self id GRA. It wont be a crime to do so.
Debbie
If they say that they're trans, then they're trans, under the current doctrine. That's the effect of the current Equality Act provision and will be further codified under the proposed amendments to the GRA.
So, no, nobody will challenge a male person in a female space now. It would be considered discriminatory tor do so, and anyway, there are no "facts" to establish in law any more;
"Oi what you doin' in 'ere mate?"
"I'm a lady"
"I do apologise Miss. So sorry for disturbing you."
Even that exchange would be considered discrimination or harassment or some such and it would be utterly pointless in any case.