Mushy,
I comment on the situation as it is applied in Scotland, (and make the presumption that similar arrangements apply in E&W). Applying fire safety provisions in compliance with the Building Standards usually follows the Technical Handbook explaining how to achieve the needed compliance. In the Introduction to the Technical Handbook, Part 2 Fire Safety is the caution " Persons with obligations under the Act (the Fire (Scotland) Act)require to carry out a fire safety risk assessment which may require additional fire safety precautions to reduce the risk to life in case of fire. For example, measures to reduce the risk and spread of fire, means of escape, fire-fighting equipment, fire detection and warning, instruction and training. Other measures are prescribed by regulation. The risk assessment should be kept under review."
Once the building or refurb is completed, the building may comply with Building Control approval (by whatever approval route is applied) but the FR Assessor may actually find the situation after occupancy requires some additional fire safety provisions. (the difference between the 'paper design' and the reality of a working environment).
As our colleagues have stated earlier, some fire safety elements rightly derive from the BC approval such as fire alarm systems and emergency lighting etc., and normally by following guidance from elsewhere, such as ACoP's, CoP's or British Standards these systems will be right, even after occupancy.