Mine fires up into a smooth idle immediately and always has done 
Do you hear the in-tank pump prime when you open the driver's door? If not, that's your problem.
If you do hear it, I'd suggest fuel filter and / or in-tank pump might need looking at. The in-tank pump was revised at some point in the MK5's life and I threw one in mine when it started getting noisy.
Cheers, I can hear it click and buzz for a few seconds when I first open the door. The fuel filter was changed about 2 years ago so that should be fine. What's a rough price on a new in tank pump fitted do you know?
I think it was about £150ish when I did it last year. Was it a genuine filter? They have a pressure regulator built-in which if it fails, allows fuel to drain back and reduce the pressure. Aftermarket filters aren't as good as VW ones.
Next time you start the engine, try pulsing the ignition key a few times and then crank it over. As well as the door triggering the pump prime, I think it does it on the ignition too. If it starts better then, it does sound like the pump is getting tired, or the filter has a defective valve allowing pressure to escape.
