K12 Non Starter

Hey Guys, can anyone help with any idea's on a 2005 1.2 that ocasionally won't start. It's got keyless entry and ignition. The ignition comes on but when you turn it to start the engine, nothing happens other than the radio going off etc. Battery is fine and lights don't dim when you turn they key. Eventually it will go when you try it but it may be after several minutes or hours. My first thought was a dodgey starter solenoid. Anyone else had this problem? Cheers