From what these employers have to do according to Stonewall
- Find out the facts
The first step is to make sure you are educating yourself – so be sure to learn about trans identities and experiences.
Ok then, let's visit the link they provide -
How do you know you’re trans?
Many people know they’re trans from a young age. Some trans people might not have the language or understanding of what it means to be trans until later in life. But it is always something innate and absolutely core to your sense of self. It’s not something that’s a fad, a 'lifestyle choice' or something that comes and goes.
It is an essential part of who you are that can’t be changed. If you aren’t recognised as being the gender you know you are, it’s extremely damaging
That's not really answering the question at all is it? It's like a politicians answer.
But what about public toilets?
Trans people can and have been using the toilets that match their gender for years without issue. This is another media-generated ‘debate’ (yeah, because God forbid women fucking debate anything, eh Stonewall?) , and it’s actually having a negative effect on many cis people too; people whose appearance doesn’t fit the stereotypes of male or female are increasingly being challenged for simply going into a public loo.*
(notice that it's all nice and simple according to them and they address none of the complexities or dangers that go along with all of it).
Having facilities that everyone can use – toilets and changing rooms with private space – is really sensible and many businesses and institutions have been taking that approach without incident for a long time now. (and how much did female employees actually get to have a say in all of this? A real say that didn't involve them being shamed, or being at risk of being 'educated' or being sacked if they didn't agree?)