The Equality Act 2010, which contains the single sex exceptions, is not about "inclusion" at all. That word appears in the act four times, only in reference to the inclusion of terms in the act.
The Equality Act is about discrimination only, and refers to diversity and equality.
It seems that others, probably HR depts, have chosen to add "inclusion" to Equality and Diversity to make it seem as if inclusion has legal relevance in relation to the Equality Act. It does not.