If a PhD, career and health is lost due to gross negligence of supervisor and university, especially a proven case, how to fight such a case in the UK university? Is submitting thesis better the option or compensation?

Not sure how you would prove that or that anyone would take your case. I suggest you submit what you can and move on with your life if it's that bad.

Tautology. How is it 'proven'?

I tried getting on but its great burden to carry. Well, you people are right, they don't take cases and throw you out even if they agree they were wrong.