I have just looked at the installation instructions and see that you have to strip the whole pump apart. Is this necessary as the only bit to change is the plunger part which unclips easily. Any advice would be appreciated from experience.

TBH, no need mate. Just be very careful with it and work in a clean environment.

Thanks Harry . Stage 3 here I come!

Having done mine myself on my last Octy i would say follow the Instructions. You may well be able to do it by missing bits out. But the instructions are as they are for a reason. The last thing you want is to **** up the fuel pump as this could lead to all sorts of problems.

As Harry says ensure you do it in a clean environment. Preferably by removing the pump complete from the car, swap the internals and then refit.