Hi, 
I made a kayak with a class group a while back. It was an epoxy resin infused laminate with a gc50 gelcoat from a polyester mould. The end result was quite good except for one area where the laminate is quite porous. The cloth is wetted out and structurally sound but due to a very small undetected leak there are air pockets in the laminate. 
So, I'm not terribly bothered about the cosmetics, but do need to seal it internally and externally. I intend to lightly sand the outer surface of the gelcoat, remove any small flaky bits that cover air pockets and then squeegy on a coat of something. What should that something be? GC50, thickened epoxy, Black epoxy repair filler,etc... Internally, the laminate has the texture from the peel ply, so what would be best there? I don't intend to sand internally at all as the surface layer is kevlar.
Thanks in advance,
Donnacha.

I'd check out EC's kayak repair video and watch how they use release film to get a smooth finish with regular epoxy laminating resin on the outside of the kayak. 

For the inside, the peel ply finish will likely give you sufficient key if you dont want to sand it, so all you need to do is clean the area thoroughly and then apply some epoxy.