Dear Tilly,
When you tried and failed to start, were there any electrics at all- controller lights etc? Or did it make a weak choking attempt to start?
No response at all could be, as jno suggests loose battery lead - tighten these and grease.
Choking sound and then 2 days later battery fine suggests you have it checked out with your mechanic.
Dry cold air lets engine work livelier than damp warm air - any weather changes from failed to start and then OK? Was your car outside overnight before failure - I suppose you didn't then push into garage to reach O.K.!
No expert, just a history of problems, but maybe "temporary battery short - if such a thing", fine crack in alternator, loose lead to starter motor.
Nothing worse than a random temporary fault, at this time of year especially! Wait for car geek on here maybe but a professional check seems worth the cost.
Kind regards,
SIQ.