For you or for a customer? Wood or PVC? Either ways I would say yes, fensa isn't a legal requirement, but you may have to inform the council and pay a few quid for them to come out and verify the work.
The BCO will look for the engraving on the glass, that's all he's really interested in. I'm assuming because you're asking about glass you don't include the firedoor, intumescent smoke seal or hinges or door stops.
If the door is manufactured as a fire door, and you fit it accordingly; it meets all the requirements.