I am currently signed off from teaching. If you are currently too weak to work, (don’t reduce your hours further, I was advised against this) get your GP to sign you off first. 100 days full pay, then 100 days half pay or get your GP to request amended hours for a while.
That gives you time to seek advice from your Union. And if you are not in one, join one now online.
HR support the school, Occ Health support the school and you, but your union will support you first.
Remember the school have a duty to apply reasonable adjustments, which could include rest times, there is also Access to work payments/aids
The school might choose to dismiss through ill health (might be beneficial), however, your union might seek a payment settlement too.
i would imagine that last eight years of your pension would only be the average scheme, so check your figures on the teacher pensions website (I am sure that you have already).
A good quality pension/investment company would also advised re. Pensions through ill health.
i cannot see myself returning to teach and am currently asking my Union rep to be my advocate and help me out, what I thought would be straight forward is more detailed and complicated and I no longer have the concentration or energy for it all.
very best of luck Ali