I would recommend the excellent colour references on the IPMS Stockholm website:
Urban's Color Reference Charts - Part I
You should also check out the two articles they have on Beaufighter markings:
Camouflage & markings - Bristol Beaufighter (Part 1)
and
Camouflage & markings - Bristol Beaufighter (Part 2)
As for the cockpit, I alwyas use cockpit green (Humbrol 78) for RAF planes.
With those articels, you can't go wrong!