First off, big hugs for what you are enduring. Are you wanting to move that far simply to get away from your mom and current situation, or because of that and a desire to live in your hubby's hometown area and near his family? If it is a bit of both, all should be fine.
If it is only to get away from your mother, you could move just far away enough to keep her out of your business. Although the cultures are similar, there are a LOT of differences between the US and UK. You mentioned being in that area and with his family came naturally, so it sounds like you will adapt easily, for the most part.
There is no need to spend your life miserable, or subject your children to a miserable life, trying to please or even be near a family member who won't allow you to be happy. I don't need to know the situation, but I do feel you know in your heart and mind you would be happier elsewhere. Maybe (again, I don't know the situation) you could have a slightly more normal relationship with your mother, or at least be in control of when she can contact you, from a distance where she isn't able to be around all the time.
It does sound though, like you are doing your research and soul searching, and not making a hasty decision. That is the wise thing.