XUD Starting Problem (Peugeot 306 1.9 DT)

[Gaz85]

Been having problem's the last couple of weeks when starting the car for the first time of the day the glow plug light wouldn't come on and the engine wouldn't turn over it would just click every time you turn the key but after a while of turning the ignition off and on and trying to start it the glow plug light would come on and the car would fire straight up anyway after reading a few comment's and what not i decided to change the glow plug relay yesterday. This morning i went out the car started up with no issue's and was fine through the day however after i had parked up at home and left the car for maybe 3 hour's tops i went out but the same thing has happened again where the glow plug light won't come on and the engine won't turn over all you can hear is clicking from the engine bay. any help would be greatly appreciated thanks all.