Thank you for all the support, you lovely cat people. Everyone at work was really nice. They've been told to keep checking on me, and given guidance about what to do if I keel over.
The manager admitted she'd spoken to someone who works in HR, which must be the point at which she hastily backtracked. She hugged me - that was awkward!
I so wish I had a copy of her saying she was going to terminate my contract, even on voicemail if not in a letter, but sadly it was just on the phone. I do have a copy of the letter where she said she was going to put on me on sick leave though and I'll certainly be keeping that.
I remember your problems with the NHS too, NotMyCat.