OP there is a man like this my extended family, he is utterly fixed on always staying in the same impractical house for unclear reasons, however unhappy it makes him, his wife and kids. He has autism, although in addition to that he is a selfish person.
I would say that nothing will change his mind - no amount of logic, or discussions, or presenting alternative plans, or talking about the future.
It sounds like your dp actually has a pretty miserable life himself - apart from football once a week he is basically working in a bad night job or sleeping or exhausted in the flat. For some reason he won't move even though it is making him unhappy!! So I think trying to reason with him won't work. He isn't even willing to move to improve his own quality of life!
I think your own solution sadly is to leave the relationship and forge ahead on your own. I understand this isn't what you want and will be difficult, but otherwise you will be having the same discussions with your dh in five years time.
Could any of your relatives lend you some money to help you move into a new place?
Would your dh oppose you taking the kids to a new area?
Do you have any roots in other areas of the country?