Now that there has been a ruling, and the government has endorsed it (not that I would expect KS not to endorse a Supreme Court ruling, as a barrister by profession) the problems can't be kicked down the road any longer. We know that transpeople should use facilities designated by their sex, and we know that 'sex' means biological sex as observed at birth', whatever we have been told to believe before now.
How that will work pragmatically remains to be seen. I am not sure that compelling premises owners to rejig their plumbing and space to create 'third spaces' is either reasonable or realistic, and am not sure what that would achieve anyway. If someone feels threatened by having to declare their true sex by using the relevant facilities (which I understand) aren't they going to feel the same about using the designated 'trans' ones?
Are people suggesting that transmen and transwomen have facilities separate from one another? Two extra sets of toilets (so four in total) in a small cafe? A separate changing room in a small boutique-style shop, so three altogether? Separate wards, wings and so on in a variety of settings? that is likely to be ruinously expensive for businesses and public services, so I can't see it becoming mandatory (and nor, IMO, should it be).
The answer should be to move towards acceptance of transpeople as transpeople, so they can use sex-based facilities without awkwardness. Why would that be problematic? I appreciate that after living through such divisive times it can't happen overnight, but it's surprising how quickly tides of opinion can turn where there is a will, and I genuinely believe that most people are already tolerant of transpeople - just not prepared to have them drive every agenda.