I have become addicted to toilets after @Keeptoiletssafes education so let me link
Full Approved Code of Practice and Workplace Regs 1992
https://www.hse.gov.uk/pubns/priced/l24.pdf
There is nothing in the regulations that suggest toilets need to be in a seperate lockable room formed by a partition. Toilets are to be bounded by cublicles or rooms. Toilets bounded by cubicles need to be bounded by a facilitiy with entrances and exits to make it single sex.
If cubicles are designated as rooms then the rest of the regulation makes no sense at all. Mixed sex facilities can only be in seperate rooms.
Further clarity is offered with the provision disabled toilets where it states, suitable toilet accommodation may take the form of specially designed cubicles in separate-sex toilet washrooms or a self contained unisex toilet;
Building Regulations which give life to the details of the Workplace Regulations 1992. They are totally single sex focused. See page 49 https://assets.publishing.service.gov.uk/media/66f6c5eec71e42688b65ee11/ADM__V2_with_2024_amendments.pdf
https://www.hse.gov.uk/simple-health-safety/workplace-facilities/health-safety.htm
HSE BOOKS © Crown copyright 2002
A guide for employers
New and expectant mothers at work
First published 1994
Second edition 2002
ISBN 0 7176 25834 https://www.qub.ac.uk/directorates/EstatesDirectorate/UniversitySafetyService/FileStore/Filetoupload923384en.pdf
Resting facilities: Rest is important for new and expectant mothers. Tiredness increases during and after pregnancy and may be exacerbated by work-related factors. The need for rest is both physical and mental.
Hygiene facilities: Without easy access to toilets (and associated hygiene facilities) at work, due to distance, work processes or systems, etc, there may be increased risks to health and safety, including significant risks of infection and kidney disease.
Because of pressure on the bladder and other changes associated with pregnancy, pregnant women often have to go to the toilet more frequently and more urgently than others.
Breastfeeding women may also need to do so because of increased fluid intake to promote breast milk production.