Complex situation - Best housing option to pursue

[Toomuchpinot]

I desperately want to leave my marriage but find myself in a really difficult situation.
My husband has a serious long-term illness and his earning potential is very limited. We are both in our mid-40s. He is naturally against the separation because I have supported him financially as well as done everything around the house and with kids and carried the whole mental load on my own.

My income is £63k, he only earns something like £600 a month, however without my income he would most likely be entitled to UC and could possibly be classified as disabled. I have paid for everything for the last few years. I would like to have the kids at least 50% of the time as his ability to look after them is limited.
My pension around £100k, not sure of his, maybe £50k.
Two daughters, one in secondary and one still in primary.

Outstanding mortgage 105k. The bank values the house at £400k, zoopla at £420k, the nearest sale to our house was for £380k mid-last year.

Option 1. Sell the house, split the equity and both buy a flat. I understand he is entitled to more of the equity due to his limited earning potential.

Option 2. I buy him out. Not sure if this is even feasible with the current interest rates. Certainly not if the house was worth more than 400k.

Option 3. We both stay on the mortgage and I move to a rental. I wouldn't be able to pay both mortgage and rent. Would he be able to get UC or other help due to his illness to cover costs? Would this weaken my financial claim to the house even further?

Option 4. He moves to a rental and tops up his income with UC, maybe with CB as well.

Any other options? Not keen on any nesting option.

Thanks.

I think his first port of call should be to try to get pip, it's not means tested. If he qualifies for this it is extra income that will make it easier for him to rent using a mixture of income and uc, usually he will need to not own a home to get uc, nor can he have savings over £16k. Shared ownership is a potential for him as he can invest his divorce settlement then rent the remainder using uc

Thanks will look into pip.
I was told he might still be eligible for UC even if he has a mortgage/owns a home, but not an expert here.

I thought on UC you can get help with rental but not mortgage but you'd need to check this. Also if he has savings ie equity from house he'd not be eligible so PIP may be a better route for him.
Ultimately you'd both end up with less after the divorce but if he can't work it's not necessarily your job to support him if you are having kids 50 50.
Sounds like you'd get enough each from the sale. If this was enough to buy a flat for each of you (you can top up with mortgage) then that may be the fairest way to go and then equalise the pensions. You don't necessarily have to give him more equity, that would depend on what you agree. Does he want more equity?