Any advice on a problem with my L series would be appreciated.

Had a 'rattling' noise from direction of fan belt for a week or so and starting to think its time to replace it, especially bad in morning when engine cold. I had a similar noise last year and my friendly mechanic changed the belt and all fine afterwards. This morning the car would not start, acted like battery almost flat but it's reasonably new and has been fine up to now.

Got it going with a spare battery no problem but now I note when driving the red battery light is flicking on occassionally.

Could be alternator I know but as I am getting the noise from the belt area could it be just this that is not allowing the alternator to charge the battery enough?

Once running car is fine, no stalling or dying ...

Cheers.

Sniffer

The fan belt would squeal if it was slipping. If you have a rattle it could be that one or more of the alternator bolts are loose or that its bearings are gubbered.
Either way if the charge light is flickering it isn't charging sufficiently so it's likely it needs replacing. Just make certain all connections are tight first.