Thanks for your reply, Dr Leela...
The boot I mentioned was the work boot I was wearing when I was doing the gardening. (My trusty blundstones!)
I passed out after the initial fall from the pain, but in the last few weeks, have been using meditation techniques to minimise the pain.Also MLD for removing oedema.
I have access to a camwalker (removable cast), but will wait for advice from the orthopaedic surgeon. The GP seems to think that the injury will need surgical intervention, as the ligament is completely torn.