(I think they mean sex but hey...)
assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/719398/Gender-separation-guidance.pdf
Some useful clarification about the curriculum and single sex sport. I've only glanced at it but it looks constructive at first sight. I did notice para 13:
"It is permissible for toilet and boarding accommodation facilities to be separate as they are captured under existing statutory exceptions. Separate toilet and washing facilities must be provided for boys and girls aged 8 years and over pursuant to Regulation 4 of the School Premises (England) Regulations 2012, which falls within the exemption provided for in Schedule 22 of the Equality Act 2010...."
Doesn't seem to allow for any doubt.