The first question on a Nuneaton loft is which roof structure you have, because the town has both in quantity and they are different jobs entirely.
The Victorian and Edwardian housing around Chilvers Coton and Stockingford has cut roofs: rafters and purlins, with space that can be opened up and strengthened. These make the better conversions where the head height is there, and head height needs measuring rather than assuming, because floor build up and insulation take more out of a roof than anybody expects.
The interwar, post-war and modern estate housing at Weddington, Whitestone and Attleborough is trussed. A trussed roof has no usable space until the structure is reworked, which is a proper structural job rather than a matter of boarding out. It is routine work for us, and it is not the same price as a cut roof.
The permitted development volume allowance is forty cubic metres on a terrace and fifty on a semi or detached house, which sounds ample until a dormer is drawn. A dormer facing the road is not permitted development anywhere, and in the Abbey conservation area the Article 4 direction tightens things further.
Escape, fire separation and stair position are all Building Regulations matters and all far easier to solve on paper than after the joists are down. Our loft conversion page goes through the structural options.