thanks for the advice guys, I will check those guys in Wokingham out as I'm only round the corner in Surrey. I say 12mm marine ply purely because I got a huge sheet for 30 quid so its cheap and easy to make the first attempt out of. A good friend of mine does composite stuff so as soon as I have the shape and some fixing points sorted on the car, I'll take the prototype down to my mate and have him knock one up out of carbon-honeycomb sandwich.
I asked Demon Tweeks if they sold anything for the supports and they suggested light stays so bought a pair of these:
http://www.demon-tweeks.co.uk/Motors...s/1599/0/22804
worth a try??