disco 300 tdi starting problems help.

Hi first time poster long time lurker,
I have my disco for 2 years not caused me much trouble until recently,
she refused to start on morning after being idle over the weekend it was ticking over fine just not starting, all the lights are on as normal etc. got her fixed up and serviced last week pre mot the garage said the battery was only holding 9 volts, so went out and bought a new battery straight away, she started after three or four seconds of ticking over, next morning back to square one ticking over with no start, I've had the electrics checked not long ago all good nothing drawing unnecessary power, alternator works fine 14.5 volts or so, obviously I'm not really mechanically minded bar the few basics.
does any one have any ideas on what it could be?
i think it could be plugs or starter motor?
i would appreciate any help its turning into a bit of a money pit!!!!
oh yeah the penny trick is brilliant a tip of the cap to the man or woman who came up with it pity i bought 2 belt tensioners trying to sort it out before hand.:doh::doh:

glow plugs , and check earth strap on engine , would be a start. also replace your lift pump, these do cause lots of problems . only cheap to replace, and at the worst you will have a spare , which you should carry anyway...

fuel filter is a cheap job one to rule out

silly question how much fuel u got in the tank

cheers guys
there is about half a tank first thing i checked. If i jump it it will start first click she's had a service new filters etc. I will check out your recommendations guy s, its a bit of a learning curve mechanically with an older disco and a money pit