I finally managed to get a physiotherapy appointment yesterday (albeit remote) and have some good advice on managing my back strain. Life is somewhat easier as a result. The short version is never believe medical advice that you read online. With any luck I will be properly mobile again in a week or so.
Meanwhile I am getting some reading done, that being about all I am good for right now.
It looks like my optimism about COVID-19 cases in the UK was misplaced. Yesterday there were over 1500 new cases, and today the government website is mysteriously unavailable, which suggests that someone is trying to massage the data before making it public.