The problem is, our Equal Status Acts mention gender, not sex -
The Equal Status Acts 2000-2018 (‘the Acts’) prohibit discrimination in the provision of goods and services, accommodation and education. They cover the nine grounds of gender, marital status, family status, age, disability, sexual orientation, race, religion, and membership of the Traveller community.
Pretty much all of our equality legislation mentions gender instead of sex, which makes it pretty much meaningless if people can identify into whatever gender they please.