Yes, he's wearing the prototype, and as far as fellow collectors and I have agreed, the only type of battldress worn during the BoB. It may have been trialled, but I think it was only later sent to stores.
Of course post-BoB is another matter, but currently I think sending kit references which exceed the BoB date would just confuse the team into modelling this type for the BoB.
I've already seen examples where the team has used post-BoB kit (type 21 microphone modelled, mark VIII goggles shown in a poster for the game etc)
It's also worth noting the differences in the Other Ranks and officer's uniforms: material (as you say), also the officers tunics had buttons on the two lower 'flap' pockets which the Other Ranks' versions didn't have. Of course the rank insignia was different, and the Officer's would have a tailored cut.
Let's be honest, modelling all these differences would just be a lot of time spent pleasing a minority of people
it's still useful for the future, I suppose.