Hi
The best book for grp car repairs, including moulding, was by Miles Wilkins, 'How to Restore Fibreglass Bodywork' - unfortunately long out of print. But you can now buy a reprint from a Lotus Books in Germany. It comes combined with Wilkins' book on car painting. See:
http://www.lotus-books.com/additions.html You can pay in £. Order form:
http://www.lotus-books.com/order.html Just for moulding, not repair info is the excellent and more recent 'Competition Car Composites' by Simon McBeath, publisher Haynes. Still in print and covers carbon fibre as !well as grp, and all at shed scale!.
If anyone needs to buy fibreglass supplies in Scotland, I've found Allscot very helpful. Trade prices, DIY quantities, and open late some evenings as well as Sat morning. And no, I don't work for them, or get a discount!
Web:
http://www.allscotltd.co.uk They're in Glasgow, but do mail order
Cheers
MikeW