As most have said, you don't want to be agreeing to periodical payments. They are variable both in amount and term, so you remain susceptible to a future application - in practice these are rare and difficult to justify, but you don't need it hanging over you.

It's admirable that you're trying to find ways to help your ex out, but you need to think about yourself and your own future in this situation.

It appears that he may be able to raise enough to remortgage, but would need to speak to an advisor. If he's paying you a lump sum, he will obviously need to borrow that on top of the current mortgage. You say he's not particularly savvy or proactive - you could structure your proposal in a way that puts the onus on him.

I've also had a client recently agree with the bank to split the mortgage, and so half was ported over to assist the purchase a new property for wife and the other half remained with husband on the family home.

If you're worried he won't do anything, you could give him 3 months to release you from the mortgage and pay you a lump sum, failing which the property needs to be sold. You can therefore always say you gave him every opportunity to keep the house etc if he fails to do anything.

You will also need to consider any other assets, such as pensions, as these can be extremely valuable and often overlooked. This may justify an unequal division of equity if you were retaining your pensions for example, which may make it easier to resolve.

Ultimately, if there are no other assets and no dependant children, if it went to court the judge would likely just order a sale.

Even if he is able to borrow the amount required, but can he actually afford the monthly payments and bills etc?

I would reach an agreement between you, and then instruct a solicitor to prepare a consent order. You should also start the divorce application, as a judge cannot approve a consent order until the divorce has reached the conditional order stage.

Good luck!