[rcdart]

Easy fix, no risk.

CA all the bits you can back into place, use balsa to fill any holes, smooth off the inside, then lay up the inside with a couple of layes of 2 - 4 oz glass and resin. Sand the outside as smooth as possible, fill with a light mix of milled fibre and resin, then layer with 3/4oz cloth on the outside, sand and paint.
If having trouble CA'ing the bits back in place, rub micro balloons into the cracks, then pour in the CA.

Good luck!