If they were serious about helping people with disabilities who want to work they'd introduce something like we have here in Sweden.
We have a system where you can be 'signed off' for varying amounts and the benefits system reflects this. Is isn't all or nothing. So for example because of autism I've been assessed as having 50% capacity. So I am 50% sick pensioned. I will never have to be assessed for this again as it's not something you get better from. So I receive 50% disability benefits, which has no bearing at all on the other 50%. I can work 50% and earn millions (I wish) and it doesn't impact my disability benefits. And my DH's income is irrelevant.