So my site was down for quite a while there yesterday, and I was none the wiser.
Apparently an unannounced Apache update being done on a server at my webhost managed to nuke my site. However, thanks to a responsive and helpful support team, they managed to get it sorted, and the site is back up and running.
There still appears to be some minor issues behind the scenes but they should get sorted out shortly and shouldn’t affect the front-end.
So it’s business as usual.