You can ask the nurses to tell people that you're asleep while you're in the hospital. When you get home you can put up a sign saying 'shhhh Mum and baby are asleep - please come back later' on your front door and you can leave a pencil & post-it notes beside the sign so people can leave a message if they want.
MIL invited all DH's aunts and other assorted family members to my house after Yasin was born (without asking me first!!!). I gave them all about an hour then I just said that Yasin was due for a feed and I needed some privacy so I was just going to my room. Then I stayed in there until they left. MIL is pretty stalky and persistant so she was there until 3 am but whenever I wanted anything I just sent DH an SMS and he bought it in. When Imran was born she didn't bother trying it on again.
When they all get too much you can just run away. I still do it. Other excuses include OMG what's that smell? The baby needs a change. It's time for babies nap (even if he just woke up - I just say he was so overtired he couldn't get to sleep. I've been trying for an hour so now i need to pop him in his pram and go for a walk.). I need to go to the shop and buy nappies (and stop for a coffee & some groceries). I promised Yasin I would take him to the park. I'm sure you get the picture and you're a creative woman so you cab come up with your own excuses lol.