Job done
Not an easy task unless you remove the fuel pump which is a daunting task on its own.
Needed to use 8 and 12mm ratchet spanners to remove and replace nuts and glow plugs.
A telescopic magnet was used throughout the job for rescuing dropped spanners and nuts, and it was very handy for screwing/spinning in and out nuts and plugs.
TOP TIP
To get the small nuts back on to the plugs was really difficult so I stuck the magnet on to the plug to magnetize the thread and then stuck the nut on to a screwdriver with some grease, lowered it into position until the magnetized plug grabbed the nut, I was then able to spin the nut on a couple of threads using a screwdriver blade whilst the thread was still magnetized..
The easiest one to do was number 4 and the hardest was number 3.
Hope this will help
future GTD owners