Well, it looks my battery is buggered. Since my last post, whereby I fully recharged the battery, I opened the bonnet today and put the volt meter on it - 12.1v! It was 12.9v when I took it off charge.
So time for a new batt I think. Question is this - because of the constant stop start, will I regular battery get knackered quickly and hence I need an expensive and dedicated stop start 12v battery or do most Jazz hybrids have a normal battery?