Nobody is banned from toilets, changing rooms or indeed anywhere else, but males must use the male facilities and females use the female facilities. Where possible gender neutral facilities may be provided AS WELL, but not instead of.
There will be a huge amount of disinformation about this rolling around today, but nobody is banned from anything, other than intruding upon the opposite sex.
"The updated guidance is expected to make clear that employers and service providers should provide single-sex lavatories, changing rooms and washing facilities on the basis of biological sex, after the Supreme Court judgment in April last year that held the legal definition of “woman” in the Equality Act referred to biological sex."
https://www.thetimes.com/article/b0750d21-426a-45d5-8cee-9578e33c6d9c?shareToken=a2e55a09e70500c14807d8eb1713db03