From a workplace regs perspective - I think that the imminent EHRC update will also support.
The EHRC’s interim update essentially said that trans people should be prohibited from using single-sex facilities aligned to their gender identity in the workplace. I think this should include places where people change - so female children cannot change a place where a man will change as that is not a single sex space.
I haven't reas teh KCSIE latest draft but safeguarding would apply to residential settings
Safeguarding and Child Protection (e.g., Keeping Children Safe in Education - KCSIE, Education Act 2002 s.175): Schools have a statutory duty to safeguard and promote pupil welfare. This includes appropriate staffing, supervision, and risk assessments for residential visits. Staff must avoid situations that could lead to allegations or harm. Overnight arrangements require clear protocols for access to rooms, night checks, and boundaries.
Health and Safety at Work etc. Act 1974 and related guidance: Requires suitable risk assessments for educational visits, including accommodation, supervision ratios, and emergency procedures. The Department for Education (DfE) and OEAP National Guidance emphasize effective supervision.
Equality Act 2010 (sex as a protected characteristic): Allows single-sex accommodations and services in certain circumstances (e.g., for privacy, decency, or safety). Schools can (and often should) arrange single-sex pupil sleeping areas. For staff supervision, matching the sex of the group supports privacy and dignity, especially during changing, sleeping, or personal care. Exceptions exist, but blanket policies must be justified.
Teachers' Standards and professional conduct: Teachers must maintain professional boundaries and act as role models. Staying in or entering pupil rooms (especially alone or opposite-sex) carries safeguarding risks.
The school should have single sex policies and confirm biological sex. If the person lies on their record they are commiting a breach of contract and probably a criminal act of voyeurism or exhibitionism and should be dealt with accordingly.
If there is something specific happy to take a DM