Battery drain/ fault codes and symptoms

[PaudieG60]

I have a 2010 passat estate, 2L tdi.

I have been using a Carley scanner the last few months to track the fault codes.

Not all appear at the same time.

The symptoms I've noticed,

Battery drain/car struggling to start.
Flat battery (replace with new)
Car revs higher at idle (idle drops down if reved)
Fans kick in even on short drive(not sure if normal)
Heated rear window button flashing (not all the time)
Heated seats not working
Power steering get heavy if turning on bumpy surface in first gear.
Interior lights + outside lights lightly flickerin.

Now the codes,
-01134, alarm horn fault.
-02390, control/regulation for ambience lighting [E400].
-01598, button rear window.
-00834, signal for activation of Heated rear window.
-02399, control circuit for terminal 30, Interior illumination.
-U108E00, control unit in the steering wheel, no communication.
-B10A611, activation of front left seat heating, short circuit to ground.
-01650, rear side airbag crash data dr.side stored.

I'm used to working on mk2 golf's so I feel a little out of my depths here.
I have time over Christmas to get to the bottom of the issues before it goes to the garage in the new year.

Any help greatly appreciated!

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