I'd like to understand better how deep the hole is, or is if is more of a chip than a hole. If it's a large hole, than yes, a gelcoat patch will not be enough. On the other hand, you don't want to fix it with something like Marine Tex until its flush, and then paint
the gelcoat on, because you want some depth to the gelcoat. Indeed, for really small scratches we sometimes make them a bit deeper, just to give the gelcoat some "tooth."
Also note that if you use epoxy for the under-fix, you may nee dto be careful in order to assure a good bond with the (polyester) gelcoat. Read the prep instructions carefully. Contrary to popular opinion, you can put gelcoat over epoxy, but it is a bit more of a challenge, and you need to be sure there is no "blush" or etc. on the surface of the cured epoxy.
Hopefully you have a chip and not really a hole, and can just use the gelcoat, since this is your first repair. Remember not to try to make the gelcoat perfectly flush - you want it to stand bit proud so that you can "buff" it back to flat with the wet/dry paper.
Come on, can we see the owie? Please?