I have to say it is all really weird still! As like I said my car has never not started, I've had no warning lights - I'll put it down to a dud battery for now, despite the voltage readings being fine for it, it must have been causing issues somehow. 

Thanks Emily,

Renewing the (poor brand) battery may not prove to be a cure, so if it were mine, I would be going along to the recommended VAG independent as a next course of action. 
re. batteries:- simple voltage is no longer king, and neither is its ability to start the car. The car’s systems monitor things like cold cranking current etc.etc.  and this may not be up to par.

It could well be an instrument cluster issue, but the prior approach must be logical -as said - entrust the final battery and alternator efficiency testing to the independent ( Kwik Fit ?) and then take sound advice from them.

Kind regards,

Gareth. 

Emily.

I fully agree with everything Magnet has mentioned. The voltage reading and the lack of starting problems are not sufficient evidence nowadays to prove a battery is healthy, therefore it remains suspect in my view until professionally tested. (I don't count Kwikfit as professionals in this respect.)

I really don't believe I can add anything new to this topic until a proper battery test has been done.