Yes then you are right Hunter if offering a service to the Public there is a duty under the DDA to make reasonable adjustments to buildings to ensure that all members of society are able to use the service, and that under the Fire Safety Order all customers and staff are "Relevant Persons" and there must be a suitable and sufficient means of raising the alarm of fire and an evacuation plan that works for all. If providing a visual sounder there must also be a sign to explain what it means and what to do if it operates.
Usually such organisations use fire wardens to search areas such as toilets if an evacuation takes place, usually the fire wardens will have a security key giving access to toilet cubicles if locked- however nobody wants to outrage a persons dignity.