We used a company called Hamilton Walters, I think I've put a recommendation up for them on here a while back?
We where impressed with the detail of their quotation and the effort they out in initially. They kept us up to date throughout and gave good advice when required with regards to the build itself which resulted in an increase in our overall headheight in our loft as well!
The job was ran efficiently and although any building project comes with its own stress, they kept us in the loop with everything.
Have actually got them back in for some roofing works on another one of our properties which is currently on-going and so far so good there as well!
His number is: 077 8000 4007
Hope this helps!