Just done run 1 of week 4 and it went well! Going at a slower pace with shorter strides, on the advice of kind members of this forum and the Japanese slow running video, which was really helpful. Although I can't shake the feeling that I'm cheating a bit, and it's not 'proper' running! Anyway, Jo Whiley keeps telling me that all that's needed is a light jog, so it must be OK. My knees are feeling better too, thanks to strengthening exercises and warming up beforehand.
The playlist that I made for myself on Spotify really helps me keep going, and I've found that music with a steady gentle rhythm works better than thumping rock tracks. Sweet Dreams by the Eurythmics and Soft Cell's Tainted Love are really good!