A screenshot up thread indicates it’s designed for single women, not single mothers.
If the flats are designed for single adult occupancy, it’s legitimate to exclude children.
If it is to comply with the law, they will need to remove the claim that it is ‘women only’.
If they want to provide for single mothers, they can be women and children only.
None of this is remotely complicated. The complications arise for the group of people who are upset and feel excluded by female only provision. As a ‘bleeding heart liberal’, I do care about finding a resolution for this specific issue, but I don’t think it needs be the concern of providers or users of female only provision.