Hello, we are jusr about to move into a refurbished unit of offices with a small warehouse. The owner has installed linked fire alarms, the sort that would be fitted in a domestic premises. We have just been told by a fire safety company that this is not enough by law and we need a fire alarm system with the break glass units. The wiring also needs to be fire resistant. Is this correct?

You need a means of raising the alarm of fire and in most cases this is done by the use of manual fire alarm call points, also the wiring has to be fire resistant. What is more relevant, has a fire risk assessment be done and the results of the FRA will determine all the fire safety provisions required, including the type of fire alarm .

Check out https://www.gov.uk/workplace-fire-safety-your-responsibilities and all the guides you require you will find there.