Trouble starting and occasional smoke.

I have a octavia mk1 vrs which is my pride and joy. Looked after, polished every 2 weeks. I have never had any problems and its not missed a beat until 3 weeks ago. I was at a Madness concert and after an awesome night returned to my vehicle with a couple of friends ready for the off. Turn of the key the car started and all was well. The wife was driving and she stalled after a couple of minutes only to turn the key and it was as if the battery was flat just a click. I tried a couple of times and hey presto it started but belched out according to my mate a loud of smoke from the back.This could not be true, Maybe a glitch. No problems until today, exactly the same almost like a dead battery but it started after about 10 minutes and i made my way home about 1 mile. On restart at home to pop to the shops it turned over fine but on idle started to smoke for about 30 seconds. It was a greyish smoke and had quite an acrid smell. No lights on the dash so i took it for a ride with no problems and a couple of stop starts which proved to be fine.

Anyone had the same problem or can advise why this is happening. I have stuck the battery on charge tonight so we will see what happens.