Just after a bit of info, I have a 66 plate VrS 4wd estate auto.
My Engine management light appeared on dash and after diagnostics … it has showed a fault on valve 4 due to glow plug . 
Is this common? 
I only purchased the car in January and don’t want to end up in a mess. 

Youll have to give more details, what is the fault code, Im assuming you mean cylinder 4 glowplug - but what about it? Open circuit, short circuit?

 

If its simply a failed glowplug its not the end of the world and can be changed relatively easy as long as they dont snap.