might be a shot in the dark,,, but try pushing the fuel lines back into the fuel filter housing where fuel filter is. I had problems like this with my 2.0dti 51 plate. The car would be fine at starting but then I could come and start it little while later and it would turn over but not fire (like no fuel getting through). to eliminate the obvious I pushed the pipes in and one moved in I then fired up again. After a bit of spluttering it fired. To this day I have had no more trouble plus the car fires up even quicker now as there no loss in fuel pressure , I have even managed to secure the pipes with cable ties. Hope this helps
Andy, April 2010