Right, heres the summary...
Followed the excellent how to above but really struggled to get that plastic cover off... Took bloody ages and far too many things had to be removed just to remove it... Grrr...
Finally gained access to glowplugs... tested each and found number two to be dead ( no reading in Ohms) God its tight in there, so tight my 1/2" drive sockets were too fat, so left plastic cover off and ordered 1/4" drive socket set from daughter...
She bought said socket set from Aldi for £15 as a useful fathers day pressie.
I also ordered a set of deep sockets from ebay
With 10mm deep socket and new 1/4" drive stuff I removed and replaced the dead glowplug.
Started her up and bingo, the warning light has gone out yeah!
Now, that plastic cover is not going back on the way it is... I am going to cut the back of it to allow me to fit it and in future, remove it without all of the hassle. I reckon I should be able to fit a flexi " curtain" to the back to replace the rigid bit that I remove, and still be able to keep the area clean from most grime. Anyone done similar? Job for tomorrow...
Thanks for the help chaps
K