errm i'm not really qualified to answer i suppose but i'm sure someone will be along soon who is. But basically, your body will produce milk IN DIRECT RESPONSE to baby sucking for milk.
so in otherwords, nrmally you wouldn't express to produce milk, you would immediately latch baby on and let him suckle. Wether or not this is possible after a section, i'm not sure although my close friend had an emergency c section with no problems bfing afterwards.
I guess in an ideal world, no formula would be given so that you can regularly latch LO on in order to build up your milk supply, but i wouldn't want to catagorically say don't give formula whilst you wait for your milk to come in if this could be detrimental to babys health... it's a difficult situation !
I think if it was me in your circumstances, I would be latching LO on every hour or thereabouts to get the sucking message to stimulate the prolactin realease from the pituitary, and not give formula unless i was absolutely desperate an at the end of my tether. Which i'm guessing wouldn't be easy with a baby who is sleepy from anaesthetic as well as from the birth experience !