Hi N Thornton
I recently had a flat roof problem and decided to put a fibreglass roof on myself a DIY project. I came across an ebook book priced £2 advertised in google sponserd links on the web at;
It proved very beneficial it is in two sections one concerning hiring a flat roofer, i.e. questions to ask, how much you should pay, what materials should be used, how to avoid the "cowboys", what the isurance and guarantees mean etc; and another section concerned with DIY which included easy to understand graphic illustration. It was full of useful information concerning all aspects of flat roofing, how to fit the decking, different types of material, how to fit a warm roof, where to source fibreglass supplies and how to apply it etc;
Best of luck with your roof;
and hope this is of help
Regards
Fred