I know this is not a new question and I already supect what the answer is but I thought I would just run it past you to check.
My garaged 2001 FL1 TD4 developed an intermittent niggle a few weeks back, after mornings of firing up ok it would just make a noise as if the starter was moving a fraction, do it again and on the 3rd try fire as if nothing was wrong. Dash lights didn't dim and generally for the rest of the day it behaved as normal though on a couple of occasions it did repeat during the day.
It did it 3 days in a row in the recent cold snap so on the morning of the 4th I connected my battery charger and on it's scale of 0 -9 (9 being dead) it was about 2.5. I charged it and it fired 1st time and has performed fine in the following 1 1/2- 2 weeks, with more daytime running and less lights and blowers,until this morning, same symptoms, 2 key turns of almost nothing, on 3rd turn fired ok.
My obvious suspision is with the battery, it's not O.E and of unknown age but I dont want to fork out for a new one to get the same symptom next day. I am not a great mechanic, have little electrical experience and even less testing equipment so does my obvious diagnosis sound right or do I need to employ an auto electrician to delve deeper?

sounds like your Starter motor is starting to play up, worth removing you battery leads, cleaning them, whilst there off remove the + lead off the starter and clean that, wher the - lead bolts on to the body remove and clean, but it souinds like your starter has a dead spot, or solenoid is starting to stick, but you would probably just get a clicking noise without in turning over if it was the starter.
have had them before where you put a new battery on and a few weeks later the same problem occurs, as the old starter draws more juice on the dead spot.

There have been several reports of poor starting being down to the ignition switch and from the symptons this sounds like a possibility. Could also be the solenoid contacts.
The question of the battery would soon be answered by a load test and your local garage might oblige as they will think a sale is possible. Measuring the voltage is not sufficient.
Rapid clicking of the solenoid is usually associated with either a failing battery, (high internal resistance), or poor connections. Cleaning and regreasing the latter cant do any harm and helps the battery dispense the amps.

Thanks for the advice, I have ordered a starter repair kit today and I will see if that provides a cure. It failed to start 1st turn of the key again after being parked for 4 hours so it is only a matter of time until it fails completely, hope I can get this kit and fit it first!

Having the same problem here, been going on for the last 3 weeks. Check my previous thread http://www.landyzone.co.uk/lz/f9/td4-non-starter-125230.html here.

I cleaned all electrical connections,solonoid repair kit and then new starter motor and battery. It's been fine untill yesterday, but not now thats it 's getting cold again. It's clicked a couple of times in the mornings but then started.

I'm now left with changing either the ignition switch (already checked and cleaned it though) or the Inhibitor switch (auto box)

good luck