If they are just small scratches, you won't need to do any fiberglass work.  If the bottom is a solid color, then it is a good project for a do it yourself kinda guy.

For light scratches, hand sand them with 400 grit first.  Spray water and wipe it down periodically so you can see your progress.  Wet gelcoat will tell you if sanding is working.  If the scratches are too deep, then continue with below.

If I were doing it on my own without access to the fiberglass shop, I would buy some Marine-Tex in the same color of your hull.  Fill in your holes and use a fine metal edge to level it as good as you can to the normal surface.  Sand it with 400, 600, and 800 then buff it.

Do not expect the color to match perfectly.

If the bottom is metalflake, personally, I would take it to a shop.  Metalflake is not something a do it yourself person can do successfully.

Thanks for the help Mike.  The bottom is a solid white so that's why I think I can give it a try.