The military is not for you.
End of discussion, really.
You need to be able to move wherever they need you, whenever they need you to. Yes, you will get mat leave. But then you will be back to work, and possibly on operational tours, whilst your baby/ ies are little.
You will not spend your entire career in the southeast.
You need to do a whole lot more homework if you don't want to get laughed out of the careers office.
And first of all, you need to choose which particular corps you think might employ you - ie do you have an engineering degree? A medical degree? What is your current career? And why do you want to join the military? (Sadly, to get a decent maternity package isn't adequate)
I'm struggling to work out if you are serious, or are taking the piss, tbh. You obviously don't know anyone in the military, at all...
So, let's see. Over the last twenty years (as a loggie) I've only worked at the mod once - for three months. The rest of the time I've been posted every 12 months to three years. Have served in several different countries.
If you're just doing it for the job security and the cash, try the civil service.
Sorry, I'm usually quite encouraging with folks who want to join up, but you are breathtakingly ignorant, and need to do a whole heap more research before you get anywhere near an interview.
Mothers are expected to be as mobile and as operationally available as fathers. I have a friend who was in Bosnia before her twins were 6 months old. Your husband/ partner would have the same choice as any other military spouse - stay where he is and you head off for your posting married unaccompanied, or leave his job and go with you.
If your partner isn't intending to leave his job, then you need to be prepared to conduct a long distance relationship for the next 16 years, kids or no. He could always keep the kids with him, and you could weekly commute - quite a lot of military personnel choose to live apart to give their kids and spouse some continuity. Others don't, and move their families around with them.
My twelve year old is in her eighth school.
. I also have an 11 yo and a 9yo. You can put them in boarding school if you don't want them to move a lot, but we chose not to.
I think you need to sit down and give this a bit of thought, as I suspect you really aren't cut out for what the military will demand of you.