Many thanks.
I'm always pretty careful about internet medical advice (and rejecting a lot of sources) but I am following the stretching advice from https://www.geh.nhs.uk/patients-and-visitors/patients/patient-leaflets/shin-splints (which I've assumed is safe as it's UK NHS). Been doing some of the stretches they recommend - with just me ie no control group, it's difficult to know effects but certainly they don't seem to be making anything worse.
Torn knee ligament & inflamed bursa/fat pad were diagnosed by professional physio but shin splits seemed to me to be pretty self evident so I've gone with self diagnosis (for the moment).
If you can afford it I would pay to see a physio as sometimes just resting is not always a good thing. Certain injuries require you to keep moving but in a different way.