I might as well buy a battery from the car accessory place in town. I think that if i ask them nicely they'll bring it up to where my car is and maybe even fit it for me. I could shop around for 'bargains', but it'd take days for one to be delivered. I can't go and get one myself for obvious reasons.
What year is your Mini? if it has stop/start you will need an Absorbed Glass Matte (AGM) battery - most BMW cars do. These just contain a better substrate and aren't filled with water like old car batteries.and it needs coding to the car, most independent garages can do it. But the correct battery is expensive about £125