Ding repair on Longboard

Hi, I ve just noticed a 4"x 1" ding on the nose of my longboard, the surface is all cracked and has been slightly pushed in, I don't think any water has got in, its a 9' fibreglass lonboard, what would be the best way to repair this, if I do it myself are the repair kits made for different construction or will any repair kit do? Cheers