Morning NM, by sheer luck, I have just put up a guide to painting WW2 Naval and then read down to see this thread. Hope my guide helps in some way.
As for the area your looking at North Atlantic, most ships where painted in a very light grey to blend in with the skies up there. I would start with a base coat of Light Grey then dry brush Silver Grey then off white. If you can get hold of the book shown in my blog that will give you the full low down, if a ship had a dazzle camo scheme it would be individual for cruisers and above and usually changed three or four times during the course of the war. You could write a book about it but someone already has !
Best bet is to Google Image each ship name, nearly every ship of WW2 will have a few images on there and work camo schemes off them.
As for ship lists, everything the Germans built would be a start and wouldn’t cost much, Skytrex do some good value fleet packs which give a good selection of ship types for an area, plus they do convoy packs as well.
Enjoy your new period.