So I did some decent digging and found out that the most likely answer is that Dahl used aircraft V7826, with standard temperate camouflage with sky colour underwing as per August 1940 orders, possibly with Vokes filter, and likely with markings of 80SQN 'YK-?'. If you were to make a skin of this description, with say SQN markings of simply 'YK- ', I would be more than satisfied.
Just as an aside, any olive camos in Greece 1941 were probably only used by 33SQN, while any desert camos were left over from redeploying from North Africa, probably repainted to olive (33SQN) or temperate (33SQN and 80SQN). It is very likely there was a mix of olive and temperate paint schemes, but temperate seems to dominate 80SQN in this time period and is supported by photographs.
From Roald Dahl Museum
" We do have Roald Dahls logbook which covers his time in Greece in March and April 1941, but this doesnt give the number of the Hurricane. On his return to North Africa after 80 Squadron left Greece, the logbook lists the aircraft numbers Z4178, Z4194 of the Hurricanes which Dahl was flying.We do have photographs of the planes used in Greece, but these do not show the serial numbers. Ive attached a couple which I hope you will find of interest. The first (RD180261r) was taken in Haifa, Israel, and Roald Dahl labelled the reverse My Hurricane at Haifa, Syrian Campaign.' The second (RD180254r) was taken in Greece, and shows the plane at Megara camouflaged with branches to hide it from German planes. "