
Bits of GRP to cut up for body mods. Flat generally may be some curved bits too. This sounds vague but I am cutting and bending the side pods for
vents. Thinking of cutting up my old canoe but dont want to do that for as I made it art school (some 35 years ago)
I have a complete fiberglass car to scrap. It's a shame you're so far away! I'll be setting fire to it before long!
It might be easier... to get the bits you want...
Get a large mirror or sheet of glass... polish it up with some waxy substance (or lay clingfilm on it)..
And simply lay up 2-3 layers of 300GSM CSM on it...
Once its set you have a wonderful flexible material for making moulds etc 
Melamine/conti board works in place of a mirror. As above, if you make it only a couple of layers thick it should be bendable and nice, and you could then curve it and use it as a mould.
Don't forget glassfibre heats as it cures, glass might not be the best if you're thinking of doing thick-ish sheets.
Cardboard, lined with brown parcel tape is bendable, cheap and the glassfibre just peels straight off the brown tape 
great ideas. something for the weekend
I don't know how wide you need it, but Glasplies certainly used to sell rolls of it (it's flexible enough to roll) - I used some to ease the
transition between my pitched house roof and the flat extension when I decided to fibreglass the whole of the flat roof. I just threw the excess away
last weekend, after it'd sat around for the last ten years 