Can you afford that? Or is there enough equity?
Otherwise, sadly, it probably is going to be a massive compromise for the rest of you.
There are generally two systems - one where the council allocates properties, and a more common one where you bid for properties and the bidder with the highest priority score generally gets the property. The LA would assess what you bid on to make sure it meets your husbands needs.
In most places, you can turn down two options that are considered suitable, but if you turn down a third, the council doesn’t need to offer you anything else until you can reapply in a year.
I’d second that the OT doesn’t provide a totally unbiased opinion, they have to take into account how easy something would be to adjust; the costs involved, etc. They’re also looking at your husbands needs specifically - in reality, you’re going to have to compromise to find something that works for everyone.
Lists are pretty long, in general, but they vary based on area. I’m in the Midlands and it’s around two years here, for the top band, on average.
But, they have built adapted ground floor flats that are open plan and are designed for wheelchairs in a lot of the new council builds, so they’d be ideal for your husband. They don’t have outdoor space; generally, but they have lower kitchens to be usable from wheelchairs etc - so you’d probably be able to be rehoused into one of those within a few months.
It’s not what you asked, but I’d consider the wider lifestyle changes before you sort housing. If your husband returning to work isn’t likely, will he be able to homeschool so you can work? I’m a big believer that there should be a good benefits system, but sadly, we don’t have one; and I’d be very nervous about relying on ours long term. I’m also not sure how it’d be viewed if he was too disabled to work, and you were homeschooling… there’s sadly a chance the current system would see you as choosing not to work.
Once you know what money is coming from where; you’ll probably be able to make a clearer decision. Things like extending the mortgage to make the modifications; or accepting a smaller flat for lower costs but building a plan that gets your eldest outdoors to the park for as long as possible each day…
This is a hard path, I feel for you massively 