my fabia 1.6tdi is very difficult to start since replacing the timing belt and the fault lights are on

Who changed the belt, what lights are on, have you had it scanned?

hi i changed it myself i have enough knowledge to do that the engine management light is on and the heater light also the traction control light it starts but needs a lot of spinning 

i was thinking it may be air in the fuel system as the filter was disconnected would that make the light come on

Timing belt fitted slightly "out" of position...ie not timed correctly..????

If this is the problem would it start 

Yes, but it will sound terrible. 
 

as above, I would take the cam belt off and start again. 

Edited 2 December, 20196 yr by jars

It’s no 2020 but will post this as a warning. I changed belt on my Octavia tdi.

used VCDS graph to check Valve timming it was out but it reported fuel temp to low to adjust. It would not warm up when stationary so I took it for a run a mile down the road engine stopped valves had hit pistons.

Piston broke? So am I!  (Sorry)!