I have the orange gel coat (2005 manufacture) and this colour is different from the later cars.....the later ones look a bit paler (where as mine is definitely 'tango' orange). Un fortunately I don't have the RAL number.
I had a small mishap with mine and bought some 'standard' tangerine gel coat from a fibreglass supplier in Sandbach. Not sure of the colour but it was a standard tangerine they hold on stock. The gelcoat (1kg), colour and MEKP was less than £20.
I repaired my arch and match is pretty good....if you look closely you can see...but not obvious (fine for small repairs in not too obvious places).
Details if you want to try them are:-
ABL (STEVENS) Resin & Glass
Unit 4, Millbuck Way, Springvale Ind Est, Sandbach, Cheshire CW11 3HT, Tel/Fax: 01270 766685/529111