All new, or substantially refurbished, non-domestic buildings which are accessible by the public, are required to provide washroom facilities which can be used by everybody, adults and children, whether they have special needs or not.
There is a requirement for all new building work to comply with Approved Document M of The Building Regulations, The Disability Discrimination Act, and BS8300
BS8300 : 2009
British Standard BS8300:2009 - Design of Buildings and their approaches to meet the needs of disabled people, Code of Practice. This British Standard explains how the building can be designed to anticipate and overcome restrictions that prevent disabled people making full use of the premises and their surroundings.
BS8300 should also be followed for guidance on good practice in the design of buildings.