For various reasons the fibreglass panels on the MK are either yellow or blue, I want the car yellow, but, the RAL code for fibreglass gelcoat is differant to the paint codes Is it possible for a sample of the yellow fibreglass to be used to match a paint colour? using a spectrograph or some other scanner wotsit?

i don't see why not, but i don't know where could do it... halfords can't i don't think.

even if you do get a match, i think it'll still look different (gelcoat compared to paint)

would it be easier to paint all the panels?

The yellow side panels are bonded on the car, the only blue bits are the nose cone and scuttle

Not sure what they cost these days, but have you checked the price of a new Yellow scuttle and nose from MK - definitely the simplest option and possibly not much more than painting by the time you've done all the prep etc.

Would look more "finished" too.

^plus you have the blue ones to sell and cover some of the cost