I've decided my health is more important than money. I'm going to go off sick for a break and then not return. Phew it feels good.
I tried to raise a health and safety issue going through each stage of the grievance process, but unfortunately the Universe intervened and I had a meltdown at work, facing an investigation, so my decision has been made. I'm leaving. Just want a bit of respite before I have to tell them, too difficult to deal with right now. Probably better not to write resignation letter whilst so burnt out.