If you are building the 47 the wing fold is an option, you can have them raised if you want or build them extended like I did on both my Seafires. I took the four pieces that make up the top of the wings (parts# 111,107,108,112) and glued them together using a flat glass chopping board to work on then did the same with the three pieces that make up the lower wing surface (#106,109,110) and then built the kit in the usual manner.Before I fixed the upper and lower wing surfaces together I re-inforced the joins by gluing a piece of evergreen styrene into the recess where the wing fold parts would have gone and when that was completely dry glued in a few strips across the wingfold join going lenghtways just to make sure it was a strong join, dry fitting as I went to make sure my strips of reinforceing didn't stop the wing halves from fitting snugly together,just make sure you are happy the wing profile hasn't gone too flat before gluing it all together,if you think it has then use some small bits of sprue to make a kind of spacer but I'm pretty sure mine were O.K..
I just had a look to see if you can interchange the wings and you can't its either one or the other as the low raised "dome" in the wing surface between the fuselage and the cannon bays is different also the chin section behind the prop is different and the cannons as well.The colour diagram shows the 46 without the camera bay but the history at the start of the instruction sheet says it was also used for photo recce.
Upper surface is indeed Extra dark sea grey (Humbrol 123) and the lower surface is called Beige Green on the sheet which is Humbrol 90 (the greenish colour) , my sheet says to blend the H90 with Satin varnish 135 but I didn't bother and it looks O.K. to me.
Hope this helps,N.