Need to get some fine black mesh to fit under the bonnet vent holes. Needs to be pretty flexible to fix to curved surface, any idea where to buy it from ?

Something like this?
Rescued attachment PRO2209.jpg

Halfords sell it, but it's not cheap (I got if from there), I found it somewhere else cheaper after that and now can't remember where!

Got mine here http://cgi.ebay.co.uk/ALUMINIUM-BLACK-MESH-GRILL-BUMPER-BUMPERS-VENTS-100x25_W0QQitemZ200380197249QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM ?hash=item2ea7972981

try b + q and the like.

I picked up some ally mesh from B&Q and gave it a couple of coats of black satin paint. Cheap and easy to cut and form.