If the glow plugs are ok the glow plug timer has probably packed in.Does Your timer light stay on for a few seconds?
If not you can fit a switch to by-pass the timer.(new timers are about 100 quid +vat and a nightmare to replace)
Buy a spring loaded switch for about 3 quid, and pick up a live from fuse box. Take the live via the switch to your glow plugs.
When you are starting the car in the morning press your switch for several seconds, you should find that the car starts with no problems.
SKAN
November 2007