I agree the wanting to spend 4 nights a week apart bit is rather worrying.
But could it be something as simple as "baby on the way = need to maintain/improve earning power" in his mind, in order to provide financial security for you and the baby? And he thinks his best chances of that are in London?
A lot of men get like that with a baby on the way "must provide" kind of thing.
If you want a good quality of family life in a quieter location close to relatives that is reasonable, if he wants to provide financial security for his family, that's also reasonable. And they aren't the same thing, but they are not really totally incompatible as life goals.
If you don't mind, could I suggest first working out whether this is about something deeper, and if it's not, you just get your heads together and work out how to align your goals? Instead of treating it as a zero sum game where one "wins", why not try to see how you are ultimately aiming for the same things. e.g.
- A wish to be close to grandparents can be about wanting to give your child a good start in life (grandparent's affection, love and moral support, the security that comes from having an extended family around when growing up, grandparents handing on wisdom, practical help with child rearing)
- A wish to build a solid and lucrative career can be about wanting to give your child a good start in life (stable home, good role model, sufficient money, access to skills and connections)
You might also want to look at any underlying fears that are driving you both (e.g. losing out on time with your parents, loss of status/earning power/ability to provide for family- maybe sparked by external considerations like changes in health and pension provision, loss of social circle/social support system)
So maybe you want the same thing ultimately but just see different routes to it? Maybe also you need to address one another's fears?