Regarding your battery Accy, our Kia wouldn't start in the summer, it just clicked when you tried to start it.
A neighbour gave me a jump start and it fired immediately, so I knew it was the battery, gave it a decent run and all seemed fine.
I did call in
Halfords and they did a battery test, said it was OK but could do with a full charge.
I don't have a battery charger so just tried to avoid short trips and all was well.
Then, first proper cold morning a few weeks ago and waddya know, wouldn't start. Mrs Smoo had used it the day before, (also a pretty cold day), started it at our house, took the dog to the vets, 3/4 mile, then started it again and came home, so that must have finally killed it.
I was at work so couldn't help but we have Green Flag breakdown so she rang them. They came within 45 minutes, started it with a boost pack, let it run for 10 mins, tested it and it was knackered.
He had a battery on his van, (063), fitted it, 3 years warranty, and all for about £80, I'd recommend Green Flag if anyone's after breakdown cover, but not the RAC but that's another story.
Could I have bought a battery cheaper? Yes. Was I happy with the price paid, the service received, and the fact I didn't have to fanny about when I got home from work? Completely.
The moral of the story is, if I'd changed the battery when it first played up then Mrs Smoo wouldn't have been stuck that morning, but I rode my luck and paid the penalty.
Also, don't go off the price on the Euro Car Parts website, I think they just make them up for a laugh sometimes, but be careful with ECP anyway, they sell a great deal of $hite quality parts IME.
Stick a battery on it and go from there, I'm sure it will be fine.
Also a quick question, does the Mini diesel have a Diesel Particulate Filter, (DPF)? If so then you need to be giving it a good run to clear it out regularly, Motorway driving for about 20 mins was always the rule of thumb with Peugeot/Citroens with DPF's, that allows the system to 'regenerate'. Otherwise the filter will get choked if your only pottering round in it and it will go into limp mode.
(FYI your Mini may very well have a PSA engine).