Well we know the light is working as it should then 
Its just a matter of finding out if the plugs are dead now !
I would not worry about that just yet though , the battery is the more likely culprit TBH , got any friendly w/c's around you who would swap the batteries over for a test ?
Unfortunately not, I’ll take it to my mechanic, he should be able to check the battery etc, or I’ll just think sod it, and buy a new battery anyway.
It certainly turns over better when everthjngs warmed up. Then again the battery isn’t working as hard when the engines warm to turn it over?
I’ve had it on some cold mornings really struggle and it also seems to wipe all my trip computer data (mpg etc) ? Doesn’t effect the mileage mind! As I say, the dials flicker about whilst it’s trying to turn over, then when it finally does, the dials take a couple of seconds to move into position. Very odd. Only happens when engines cold, so only in the mornings on cold days...