Renault Megane 2.0 2003 engine overheat?

My Renault Megane 2.0 spung a coolant leak on motorway, the red STOP light came on and the dispaly read "Engine overheating" , it now has trouble starting, I have checked the oil and water for ingress of each of the other, no sign that this has happened, is there anything else that could have gone wrong ie coils packs breaking down, etc.
Cheers