2002 Renault Clio car will not start

Hi guys I have a problem starting my clio, I unlock it using the fob turn the ignition and it cranks over but wont start, my immobiliser light is on solid? I have tried removing the battery I've checked the relays, fuses and TDC sensor but still nothing. The ignition ring works fine as I tested that and I also replaced the battery in the fob, I can only presume its a problem with the key not sending the correct code to the ECU or UHP although I have tried to reset the immobiliser and ECU bit still no cure! I cant afford to call someone out as I was laid off a few weeks previous, It just so happened to be the the same morning I was going to trade the car in. Any help would be appreciated??? Thanks