They were very clear with me that if I'm not fit to teach, then I'm also not fit to tutor, lecture or work with small groups or individuals. Which seems unfair because it's perfectly possible to not be able to do the job of a class teacher but be able to work with small groups or one to one. However, how could they have rules that said you can do small groups but not whole classes? Define a small group - we know from lockdown how many different ways people interpret what on first sight seems to be clear. Now that we have to teach till we're 67, I can't imagine there will be many people fit to teach whole classes till then - they'd end up with everyone claiming partial ill health retirement. Back in the days when there was funding for intervention teachers and school budgets weren't so strapped, I bet there were a lot of people who were no longer fit enough to teach a whole class but could do small group work, so their role changed to accommodate what they could do. So I can't see any way for them other than prohibiting teaching, tutoring or lecturing. I lead some teacher CPD through a local hub school and they checked what that involved before agreeing that was OK. And as they were processing my application during the lockdowns, they also checked that I wasn't doing any online tutoring or teaching (which I actually could do, as my issue is mobility).
The application process took me a good 18 months, although part of that was because I'd never been seen by occupational health. I arranged my work and my colleagues helped me out so I coped as long as I could with informal adjustments, so I didn't ever see the point of a formal assessment - there wasn't anything extra I could think of that they could suggest. That meant that even though I'd then stopped teaching, I still had to go to the occ health provider for my last school to get the necessary report that said their doctor agreed I couldn't teach. Mind you, he did ask me why I couldn't teach from a wheelchair... He'd obviously never been in an over crowded KS1 classroom!
If you apply whilst working in a school or within two years of leaving, your application is processed by whoever does the HR at your current/last employer. There's a different process if you've not been employed by a school for more than two years but I didn't need that so I can't remember what it was. I had to fill in loads of forms, supply details of my consultant, GP, treatment, how my condition prevented me from doing the job and why my condition wasn't going to improve plus the occ health report recommending partial ill health retirement.
It wasn't easy, even though I had acquired a well known, easily observable, named condition that anyone with common sense would know isn't compatible with teaching. They were rigorous: I started two claims at the same time - my pension and on the critical illness cover I'd taken out over 20 years before. I had the critical illness payout at least a year before my pension came through.