Two power cuts in quick succession last week borked the database server so although up and running, corruptions to the backend probably prevented much content being server. A quick bit of googling and forcing a rebuild of the DB engine looks to have everything back up and running.
It was also a timely reminded to renew the LetsEncrypt SSL Certificate so we are good until December again. Renewal process worked flawlessly once I had stopped Apache so its could bind onto port 443 to do the actual renewal.