Sorry mate, derv = diesel.
Glow plugs are kind of the diesel equivalent to spark plugs. They warm up on cold starts to make the first ignition easier. Is yours diesel?
It may be just one glow plug that's bringing up a fault (if it is the plugs) so it probably would start fairly normally.
Have you got access VAG COM? It's a diagnostic reader that could highlight your problem if a DTC has been logged.