I have a giant suitcase. They haven't said to bring a separate bag for theater although I'm planning on asking on Friday at the pre-op. Our hospital try and have you waiting on the post natal ward so my plan based on what the community midwife said was just to grab the things I needed, dressing gown, slippers, hat for baby, nappy once we got there. Will pack a separate little bag if needed though.
I do have a separate bag which will live in the car until baby is here, with a present for ds from the baby and vice versa, more bottled water and ready made formula in case I hit the same issue breastfeeding as I did last time.
I have bottled water as I found last time the midwives weren't great at refilling the jugs and they didn't like you doing it. A couple of protein type bars and clear instructions to dh that as soon as I feel up to it, he has to go to my favourite deli and bring me a giant baguette stuffed with brie, salami and spicy relish, possibly two.
I have written a birth plan but only because the consultant insisted and was going to write it for me if I didn't.