DIY or pay a boat yard?
Don't know the CS 27 but if the damage is serious and the keel a solid, external structure bolted to the hull I would first remove the keel. Then cut out all areas where the glass is shattered and/or delaminated, sand and grind the broken areas until you reach good, solid glass, then rebuild
with layers of cloth and resin.
If possible, remove the interior
structure so you can access both sides of the damaged area.