@sellotapechicken Can I advise that you don't rush into ill health retirement, especially as you have surgery coming up. Your access to critical illness cover sounds brilliant, but does it preclude you from ever working again? If you end up living for ages you might go mad without something to keep you active/give you purpose.
I looked into ill health retirement after my Stage 4 diagnosis, when I didn't know whether the drugs would stop tumour growth (currently they are). That was 18 months ago. If I had taken ill health retirement (though actually in hindsight I didn't meet my pension companies' criteria) I would be going spare (and broke) by now.
I'm also going to leave my daughter in a better financial position when I die if I stay in my job, even if my health deteriorates and I can't work, because my death in service benefit is substantial. And I won't have been drawing down my pensions through ill health. Death in service does depend a bit on your employer's attitude - mine keeps people with terminal illness 'on the books' so they get death in service when they die.
There are a lot of variables to consider, and how you feel now is not necessarily how you will feel a few months from now.