Well, I got the battery changed today.
Long story shortened is that they would not entertain a warranty claim or offer a goodwill contribution.
I expressed my disappointment.
They said that the Golf R battery problems related to a specific batch and mine was not one of them - they would say that wouldn't they?
However, they knocked £50 off the quote £290 so I paid £242 inclusive fitted, a Varta VAO 669 627 RA 12V 70Ah 420A DIN "Made in Germany" with a two year warranty apparently.
That's better than a Sebang from Korea isn't it?
I was originally quoted £329 and the Halfords offer was £182, Yuasa five year warranty.
So the dealer has come down £87 which I suppose is something.  They also gave me a complimentary Up courtesy car.  Quite impressed with the little critter actually, surprisingly sporty exhaust note.  Are they 3-cylinders?
A noticeable difference when starting up now.  Instant.  
My confidence in the battery is back - let it snow!   

I was worried about what Spud122 reported on powering-up the new battery.
Everything seems be ok, which is important to me:  Radio, CD player, iPhone charging, Infotainment - satnav; Apple CarPlay incl Deezer; SD card in slot 2 (music); WeConnect and Huawei E8372 Wingle, DCC, ACC, mirrors, windows, heated seats, aircon, parking sensors and stop-start.
The only thing I noticed like Spud122 I think, was that the "CAR/Driving Data" stats had been wiped.  You know the day's fuel consumption; long-term consumption and consumption since fill-up.  That does not bother me as I know I can always get 40+ on a motorway run.
Thanks again to everyone for their inputs to help inform my decision.
Peter_S