if he’s going to be literally homeless, take him in, that shouldn’t even be negotiable with your DH.
however it sounds like he’s motivated and eager to work. It also sounds like your description of ‘rural’ may mean less local job opportunities, but then he has a car so I’m not sure that would be a major issue? If he moved in a for short while, then gets a job in a city surely he then just moves back a shared house again?
I don’t understand why you think you would need to cook for him and the concern about the high standard of food he expects? Surely at the shared house he cooks for himself and he likely isn’t doing gourmet meals every night, plus other housemates need to use the kitchen so he can’t hog the space. If he moves in and you aren’t charging any rent, and he’s collecting job seekers/UC, why can’t he buy his own food?
the only red flag I would think of with what you have described is that he’s lost his job and only 2 weeks before he can’t pay his rent. Working full time at over 25, his take home pay would be at a minimum wage £1,880 per month. His expenses were rent £600, phone £50 and car £100…so a base budget of £750 including all bills, then food/petrol. If he’s out of work that’s most of the petrol bill gone, so at £30 a week for basics for food that’s £30x4, so add £120 to the £750 to get £880. That means he’s had disposable income of £1k a month, so unless he’s had a lot of unexpected car repairs, what has he been spending that on for the last 6 years since he left home? To only be two weeks off homelessness after being made unemployed he must have only had about £450 in savings. That’s the concern for me, that he hasn’t built a buffer, and if he moved back in with you, it may be that you find he spends whatever benefits/wages he gets and doesn’t save up what he needs in order to move out again.
I would focus first on trying to help him stay in his existing accommodation. Also remember he is a grown man and it will embarrass him to be moving back in with you, he has made it clear he wants to work and have his independence, so I’d exhaust everything else before giving in on that. First find out about any and every benefit he might be able to receive, have him contact his landlord and ask if it’s possible to agree a 3 month temporary rent reduction, if he’s been a very reliable, clean tenant who responds to landord’s messages quickly and politely…the landlord may been keen to hold onto him rather that taking a risk on a new tenant, especially if there have been problem tenants at the property in the past. Take a look at his CV, go to job centre appointments with him if you can, job fairs etc. These things aren’t job interviews and nobody cares if you bring along a supporter for extra eyes, ears and encouragement. Could you offer him any financial support/gift, even £20 a week may keep him just above water. If he hasn’t already got a degree, he might find that there is an option to enrol on a full time course, with a maintenance loan which could solve his money issues for quite a while…these loans only get paid back if earn over a certain amount anyway (although the timing is not good for that). Ask the landlord do they have any other properties, a room that is even £50 a month cheaper could be very helpful.
moving back to your house should be the last resort, however if not doing it is going to cause him to have significant debt, it needs to be done to avoid that as that makes it worse for him in the long-run.
Your DH should be helping. If he’s got good literacy or interviewer experience he should be using that to help your son in his job search. He also should be ready to accept your son back into the house if necessary, he knew you were a mother, and that doesn’t stop when a child turns 18. If he comments on that ask him what happens when your 4 year old turns 18…do you just throw him out in the cold? He doesn’t need to be enthusiastic about it, but he needs to accept that family comes first. The issue of the food shouldn’t come up as DS moving in should only cost a little extra in electric and water, he isn’t moving into a hotel and will have benefit income if nothing else.
the £50 phone contract, I’m wondering if it’s that high because he’s paying off a device? If he’s got a phone worth £500, sell it and put the sim into a £50 phone or an old one of your own if you have one. He doesn’t need anything fancy for job searching, and he presumably may have other devices such as laptop anyway seeing as he burnt through so much disposable income, I wouldn’t be surprised if he has a few things he can sell. Any designer t shirts or anything such as that could raise funds quickly if he is stuck. I would recommend the only things he really needs to keep hold of are the room and the car. That should be the focus, without a car it likely cuts off a lot of job opportunities and makes it expensive to get to interviews (he can likely claim interview costs back from the job centre as well).
once he’s back up and running with a full-time job he can then of course get himself back to normal.