oh everybody bugs nearly ready to go what do you all use to paint the underside of the fibreglass ie wheel arches etc ive been reading a few mixed reports on what to use and not use on fibreglass ive come up with gravitex any ideals please.

I usually use a spray can of black shutz, something like this...
http://m.ebay.co.uk/itm/350939136594?nav=SEARCH

Flowcoat on a roller.  It's made for fibreglass.

http://www.ecfibreglasssupplies.co.uk/search.aspx?searchterm=flowcoat

Nice thick coat of black schutz.  It stays softish and absorbs the impact from thrown-up gravel, preventing small star-cracks.