On the face of it I would say that that advice seems to be right but there again it depends on who advised you originally.
If it was a builder I would definately look for a second opinion but if it was a surveyor or local planning officer I would suspect they are spot on.
The fire regulations are very strict but are a bit of a minefield in how they are interpreted.
Ultimately a building regs certificate will only be issued if the regulations are adhered to so asking the local building control office for their advice would probably be a sensible move.
