I agree with @JiltedJohnsJulie.
There's nothing wrong with doing an OU degree and lots of people who don't figure out what they want to do until a bit later in life do this and work at the same time. But these people are usually very motivated and trying hard to make up for lost time.
The OP's partner lived at home until be was nearly 30, then moved to London and started this OU degree, he isn't even close to finishing it and yet all he wants to do is move back to his hometown, away from where all the jobs are, and is already talking about taking a break from a career he hasn't even started yet to look after his and the OP's future children.
If he wants to be a stay at home dad, that's fine if it works for both of them. But usually in a couple where one is a stay at home parent, this is a choice they make to maximise the earning capacity of the working parent. That means that where they live is usually dictated by where the working parent can make a decent living.
He has already got the OP to significantly reduce her earnings by giving up a better paid job so she can spend more time with him. Personally I wouldn't be working until 11pm for £60k in London either. But now she has a less well paid job which still pays an OK salary, is probably quite secure, and which she likes. And yet he wants her to give up that job, move to his hometown where she has no job and very little chance of getting one as good as the one she currently has, find some other job which will almost certainly be less well paid and involve a commute, have a baby (and either lose earnings whilst on maternity leave or go back to work when her baby is quite small), and in the meantime, what is he offering? He's not planning to finish his OU degree any quicker. He's not planning to get a full time job in the field he wants to work in any quicker. He's suggesting that he might not work at all and be a stay at home dad for a while, which he could just as easily do if they stay in the south east near the OP's current job.
He doesn't seem to get that you can't make plans to stay at home with the kids and not work, and simultaneously ask the partner who is going to work and support the family to give up their job and move to an area where there aren't very many jobs. It doesn't make sense.