Right a further update and good news. Appears the battery has to be pretty full. I put it on trickle charge today for about 6 hours and my charger shows when it passed, 80% and then 90%. I then tried it cold and it wouldn't offer to install. I remember reading somewhere about then giving it a drive. So took it out for a spirited 25 mile drive. Came back home turned the car off and a message came up offering the upgrade on the screen. So I clicked yes, put it in park and put the handbrake on and sat in the car with the key not touching anything. The I drive turned off and started upgrading and it shows progress. Took about 20 mins whilst I just sat and watched it. All done.
So the moral of this story is the battery is very key to doing this for anyone that's having problems. I will be cancelling my trip to the dealer this Thursday now. Yippee. Hope this helps all.