The staircase winds at the top and comes directly into the room (the
fire door is at the bottom hence the landing down there) At present,
there is a huge gap in the floor 2m from the wall and actually further
back than the start of the bottom of the staircase!

With the fire door at the bottom and a winder at the top, the room itself
counts as the landing.

Provided it is done in a structurally sound manner, the stair cutout can be
advanced until it is 2m above the step immediately below it. You probably
won't be allowed 1.9m if it is possible to achieve the 2m.

One problem is that it is my understanding that alternating tread space
saver stairs must be straight flights. Do you have alternating treads? Will
your BCO allow these to be combined with a winder at the top?

If not, you might have to forego the landing and firedoor at the bottom and
have a 3 step winder at the bottom and a 3 step winder at the top. The
problem with this is that it requires the landing to be before the fire
door, so takes out a chunk of the room.

Alternatively, a fixed ladder may be acceptable to the BCO, although this
starts becoming a whole lot less practical as a room.

What is the maximum linear distance allowed for the stairs from the wall at
the top to the wall at the bottom?

Christian.