What your looking for is the DDA - Disabled Discrimination Act it's the one that says that you have have doors x wide lifts so people can get to upper floors etcI'm just pricing for same at some offices but whether its mandatory I don't know . I'd suggest checking the Building Regs . or the Disabled Persons Employment Act. ( if there is such a thing)As a sparks I don't involve myself with the legal side of stuff like that, not my remit. That would be the responsibility of the management /owners of the factory ,which may be yourself of course.