summer the first week you'll be fine, it's amazing how much you do on instinct.
And as Marlena says, don't try to do anything other than feed and change. If you plan on breast feeding, be prepared to spend nearly all your time sitting around doing just that (I went through box sets of Entourage). And minutes after they have been fed, they poo, so they need to be changed, and by the time you've changed them they are hungry again.....
If you expect that then it can be very relaxing! And if you have relatives visiting get them to make the teas and rustle up some evening meals.
I'm feeling very nostalgic now, and really looking forward to being on maternity leave.