The "S" suffix on "FD30S" appears to relate to cold smoke seal.
en.wikipedia.org/wiki/Fire_door
My newer ones have a furry pile strip on the intumescent seal, you would think it was draught strip and it cuts noise penetration, but it is designed to keep smoke out.
Various widths are available, it is usually fitted into a groove in the door lining (frame). Fire doors are heavy and have a more substantial lining than most.
The strip, and FD hinges, pads etc, can be seen here
I like the PVD brass lift-off fire hinges, because these heavy doors are difficult to take of for redecoration otherwise. They are also available in stainless to suit your knobs and handles.
A professional chippy should be used to the process, as they are used in shops, offices, hotels, HMOs and three-storey houses everywhere.
First thing is to get a recommended local chippy who will know local suppliers, measure up and make recommendations before you buy. Chek er tread is a paid-for advertising site. Personal recommendation better.