Obviously I didn't contemplate the positioning of the holes the night before well enough, because they were way off. So I chased out the hole until I was happy with the positioning, then transferred the shape to the other side beore sanding and laying up carbon fibre filler and reinforcing in the over-cut area. I then set about trimming the hole on the other side, which worked out really well. Later, when the epoxy had cured enough, I sanded and primed with 2K ready for smoothing, re-tracing of the hole from the other side and re-cutting.