Help! Starting Problem Renault Megane 2.0 p-reg?

I have a renault megane 2.0 (p-reg) and have been experiencing starting problems. The immobiliser seems to be ok but on turning the key lights come on but doesn't turn over (no attempt or noise at all). I can then go to the car later amd it will start 1st time. The car will start ok if pushed off. I have had the starter motor checked and been told that is ok.