Apologies if this is the wrong Topic. 

Would anyone be able to advise me if a Landlord is legally responsible for ensuring fire safety for rooms that have been listed as  'habitable' in terms of having access to an escape window or a protected routes? I know there is guidance for landlords such as the LACORS fire safety document. I am unsure if Regulatory Reform (Fire Safety) Order 2005, covers Landlord and residential accommodation?

It does but only the common areas from the front door of the flat to the final exit to outside the building, the flats themselves are covered by the Housing Act.

If replacement windows are fitted, then they are subject to the building regulations and Approved Document B (fire Safety) volume 2: Premises other than Dwelling Houses could apply which requires habitable rooms not more than 4.5M above the ground, to have emergency egress windows, check out page 22.