I seem to remember that permanent access staircases to the loft used to require a fireproof door, as per UK building regulations, but looking at the new interactive planning guide (Basically, a guided tour of a virtual home that conforms to planning and building regulations), the staircase up to the loft conversion has no door at any point. Has the law changed, or is a door still required?
no you dont
We were told that we had to have a fire door at the either the top of the stairs or at the bottom when we had our loft converted last year.
I would think it does as if there was someone in the loft conversion and a fire started downstairs and swept up the people in the loft would be trapped. The best ones to ask would be the local council as they are the ones you need permission from to add bits to the house.
Their building or planning depts should be able to advise.