Centre computer/stereo playing up even after recent software update to give car play.

1) when switched on and set to radio radio no sound comes out until source is selected - even to another radio source (which it was on).
2) occasional boots to Land rover logo and black background but gets no further - recent trip stopped on motorway at Fleet and when started car went to logo and no further stayed like that for 20 mins or more and only reset itself near Southampton.
3) BBC News TV channel has terrible to no signal.

In my opinion, the algorithms on which the information these cars are based is way out of reality. After a succession of short summer journeys I often get the 'battery low please start engine' message. Every subsequent time though, the engine turns over at full speed. With the nights drawing in slightly I've had full lights on and no messages. I think the car just logs short journeys and assumes your battery needs charging or replacing.

could that be an issue with your alternator not generating enough electricity while car running?

i've not seen that problem --
On my third Full Fat RR
there's nothing like it.