I see I'm not unique with this.
Mind mentioning the books you found useful?
Yeh sure, they were...
Loft Conversions by John Coutts - Covers just about every area you need to know about loft conversions
Manual of First and Second Fix Carpentry by Les Goring - Couldn't have put in stairs or floors without this!
Collins DIY Manual
DK DIY Manual
The last two were great for just getting a general understanding of how to go about a task, they're fairly shallow because they cover such a wide range of stuff, I would then generally go looking for more detailed info on it.