I'm an NCT antenatal teacher so I hear about this kind of thing a lot.
I think it's really important to speak up about what you want. You will be exhausted, physically very far from being your usual self and suddenly responsible for an entirely new human being, the last thing you need is someone there that you don't want.
I completely understand why your husband wants his mum there while he's off work, but he's mistaken if he thinks that will be a good time to see her - he should be working as a team with you getting to know the new member of your family.
Bedding down at home just the 3 of you can be just the most wonderful thing to do, sometimes called a "babymoon" - have a look at this article: http://thegreenparent.co.uk/articles/re ... -babymoon/
Apart from anything else, if you keep quiet and put up with your MIL staying, you might really resent her being there, and resent your husband for insisting, and as your relationship is going to change with the new baby anyway, it's important to speak openly about how you're feeling. If that makes sense. Just be honest about how you're feeling. His MIl can come anytime and he'll still see loads of her. Plus you will need more help (with cooking/laundry etc) after he's gone back to work.
As for the birth, most places have a limit on how many people can be there, it's often just 1 person. So that should be easy to get around.
Good luck, and try not to stress!