Hi there, you are correct what you are saying about the fire doors and smoke detectors.
I am guessing that you are not converting a bungalow as if you were then no fire doors are required however 2 interlinked mains operated detectors would be required.
If you are converting a normal house (ground floor / first floor / loft) then you will need to replace all 'living area' doors leading onto hallways, stairways and landings with fire rated doors.
This is because you need to protect the escape route from the loft, down 2 flights of stairs to the exit door. You only need to achieve a 20minute rating however, 30minute rated doors are the norm and usually off the shelf.
These will not need self closing devices as this requirement also changed when the regs changed too but you will need BS fire rated butt hinges and dependent upon your building inspector, you may also need to fit an intumescent strip around your doors or within the door linings.
You will also need to have three interconnected mains operated, with battery back-up, smoke detection units fitted. These are usually positioned; 1x ground floor hallway, 1x first floor landing and 1x loft stair landing.
If you are converting a three storey house (ground floor / first floor / second floor / loft) then you will also either need to have a sprinkler system fitted to protect the stairways or an external escape staircase, in this case you can wave goodbye to at least £7k before even getting to work on the conversion!!
