Would I be right in thinking this would be a messy and probably toxic way of cutting composites?
Try waterjet 
Laser would probably work but might burn the edges of the resin laminate?? Melt out the resin from the cut area?
I’ve done waterjet before a few times. It’s great but you can’t make cuts that direct the spray back onto the part.
laser burns the CF, waterjet is fine, watch out for airtraps, could give you a bang.
The main problem we’ve had with trying to cut carbon/epoxy laminates with laser is that the matrix would burn away and the carbon would remain intact. The burn area was rather wide too, about 1/4".
Waterjet is the way to go. Can cut pretty thick pieces and leaves a good edge finish.
great information, thank you