I had two bags. One for the Birthing Unit (which has a 6 hour discharge, so wouldn't be staying overnight), and one should I get transferred to the big hospital.
Little bag:
Cheap, large knickers
Disposable knickers (I like choice!)
Disposable mat to stick on the car seat for the journey home
Maternity pads
Snacks - biscuits, dried apricots, juice cartons with straws
Clothes for baby - 2 vests, 2 sleepsuits, hat and cardigan (vest and suits were different sizes)
Bottle and a carton of formula (wanted to be sure that baby could eat in the event something was wrong with me)
Clothes for me - yoga trousers, big stretchy bra, vest top, cardigan
Book and spare t-shirt for OH (came in handy as he got squirted with blood when the cord was cut).
Washbag with - shower gel that can be used for hair too, toothbrush, hairbrush, hairbands, body lotion.
Camera was pushed in at the last moment.
Big bag:
Extras of all the above plus;
pajamas
crappy magazines to read
socks
Carseat was in the car from about 32 weeks, bags packed by the same time. Our big hospital is 2 hours drive, so I didn't want OH to need to go home for anything, and the birthing unit is in a small village (no 24 hour shops) so needed to be prepared for everything and anything!