birth plan - really need advice

I posted this last week but got little feedback
my husband was made redundant last year he was unable to find a job near where we lived and we lost our home he got a job only problem was we had to move 200 miles from any family or friends so we have no support network here I'm due around christmas (I say 18th hospital say 26th) and due to gestational diabetes will be induced on 26 if baby hasnt arrived naturally.
I had a birth plan written if bub comes before 21st then my son would go to his creche or his key worker would come here depending on time and stay with him until my in laws arrive. If baby arrives after the 21st then my mum would have finished work and was coming to stay with us for christmas
these plans have all gone to pot I'm beginning to feel less comfortable about my in laws coming as they will want to stay after bub has arrived and I will want them to go as I will be a hormonal wreck and my brother has now told my mum that him and my niece are coming for christmas dinner and instead of telling him its possible she wont be there she has pencilled it in on her calendar and telling me that its possible she wont be down as the rest of my family need her at home and that bub will be here by then anyway.
now I'm left with a few options I could transfer and stay with my mum for the whole month of december but I then run the risk that hubby wont be there for the birth, I could stick with the original plan with the in laws and insist they have to go once I'm released from hospital (I will have to stay in for 48hrs) and then on the 21st send my son on holiday to my mums for 10 days or so meaning we wont see our son on christmas day or I completely throw a hissy fit tell my mum she needs to be here for me and my family, that she sees the rest of the family every week and that me and my baby are more important than a christmas dinner
what do you think?

Woah that's complicated.

Maybe just have you, your son and hubby then you mum can come and help out when the baby is born? It could be you, your mum, hubby and your son for Christmas. If worst comes to worst and that isn't possible you could stay with your mum and hubby could try his best to be at the birth. You need to be firm with the people you want there and don't want there and also be a little selfish as you are the one giving birth and looking after a newborn.
I had tons of people inviting themselves around after DS was born, I had to gently tell them that although it was appreciated I just wanted OH and my mum there.

thanks just worried about my son while I'm in labour if there is no one to watch him then I'm gonna be alone in the delivery room as hubby will have to have him. after christmas once bub is born mum will be back in work my in laws are retired so I kinda want my mum there during her hols as the in laws can come anytime