You can get gel-coat any color you want or mix it to match. White is pretty easy to find. I would get gel coat with wax in it to fill in the gouges. The wax creates a barrier which isolates gel coat from the air which is necessary for gel to cure properly. You can also get an additive like Dura-tec and it does the same thing and does not require as much sanding as gel-coat with wax. Another option is gelcoat without wax or adding duratec. Place wax paper over it to form a barrier but I've never had much luck with it curing properly.