This is what Packingsoapandwater posted on a thread about raising the issue with these policies with your MP:
I am heavily involved in local governance. My advice with this is to be brutal and clinical.
It is only when you put their arse on the line that they stop bullshitting, and that inevitably involves financial liability of some sort. At the moment, there are no real world consequences for holding a position that ideologically opposes single-sex spaces -- so you have to nail it to the door.
Ask your MP if she will personally accept liability (political, financial, and legal) for any criminal offence that occurred due to the eradication of single-sex spaces in favour of mixed sex spaces in the climate created by the self-id legislation she supports.
Ask her if she will step down if such an incident occurs. If not, why not?
Ask her if she would be willing to publicly defend mixed-sex spaces in the aftermath of such an incident, remembering that the single-sex spaces that would be affected also extend to hospital wards, psychiatric wards, prisons, certain healthcare clinics (particularly sexual health), homeless and migrant refuges, and sleeping quarters in residential children's homes and elderly care homes.
Ask her if she would be prepared to print her opposition to single-sex facilities, particularly hospital wards, on her re-election campaign literature.
Ask her if she accepts her support of self-id legislation could be perceived as an attack on the rights of religiously conservative women, particularly BAME women. And if not, why not? Does she think that such women deserve to be informed that this is her position before the next general election?
Again, ask her if she thinks that her opposition to single-sex spaces could be construed as a form of institutional racism against women and children of Islamic, Hindu and Jewish heritage.
Ask if she accepts your letter as evidence that she had been made aware of the potential safeguarding issues inherent in self-id legislation.
Don't be wordy. Fire these points like bullets. In fact, put them in bullet points.
www.mumsnet.com/Talk/womens_rights/3964332-MP-response-In-shock
Although you need a different approach, because this is your work, I do think many of these points can be adopted to draft a note to your HR department, especially the question about openly discriminating against BAME people (as those from a number of religious groups) by abolishing facilities they particularly depend on. And then pick one or two points to start with.
I would probably first of all approach this like DateLoaf, because I think that is a non-combative approach that may serve as a timely reminder to your HR department to check the legal basis of this new policy. If they correct the protected characteristics, you can then refer to them much more easily throughout.
If they don't and because in my view it doesn't matter whether they call them guidelines or whether these are contractual obligations, it may be worth pointing out that these new guidelines do constitute new staff management and workplace policies, overriding those that were in place when you were employed. So when your conditions change, asking where your needs were considered (or better yet, where your protected group was considered), is legitimate. And asking for an Equality Impact Assessment where they have considered the possible and likely impact on other protected groups not sharing the protected characteristic of gender reassignment is entirely reasonable.
I would not say anything about Gendered Intelligence, but I would ask when representatives for the other protected characteristics will be invited, what the timetable is and who will be responsible for integrating the new guidelines with those in place for all protected characteristics. And if there aren't any others, let them know you're looking forward to seeing guidance about disability, race, religion, age etc.
But don't do any of that if your employment status is precarious. If that is the case, either find others to address this together with (say by forming an Equality Act Compliance Staff Team or a women's rights committee) or craft a letter and post it anonymously.