Well lasted 2 days from a full charge and have now had battery tested and condemned. I tested the charging circuit just to be sure that was working as it should and that was all good. Just been to buy a new battery and stuck it on. And crikey, the rate the starter turns over now is amazing. Pretty sure the warnings i got will have just been the battery but i shall report back if I see anymore - got abs failure warning last time i started it on the old battery, but nothing today on new battery.
Regarding giving it a thrash.. All diesels like a good thrash every so often, i wouldn't say i drive the car lightly much of the time tbh, and i generally do about 10-20 miles everytime i start it, on a-roads and dual carrigeways. Don't do alot of driving through town really and just walk to the local shop if i need something (unless it hammering down of course).