An emergency caesarean is one where the operation is unplanned; it does not necessarily mean that there is a serious emergency.
You will be asked to sign a consent form. You take off all your jewellery (you can keep one special ring on if it is covered with tape), remove your contact lenses and put on a theatre gown. Your midwife will shave the top part of your pubic hair (this is where the incision will be). In order to neutralise your stomach acid, you are given a small amount of medicine to drink. A drip is then put into your arm. If you are having a local anaesthetic (a spinal or epidural), the anaesthetist administers this, giving painkillers at the same time which may make you feel rather woozy after the birth. A midwife puts a catheter into your bladder. Lastly, you are tipped slightly onto your side.
Caesareans nowadays are usually performed under local anaesthetic. You lose less blood and recover more quickly if you have a local anaesthetic and you can see your baby as soon as he is born. General anaesthetics are usually only used in real emergencies (because they're quicker to administer than a local anaesthetic) or if the mother is very concerned about being awake during the operation. Or otherwise if there are medical conditions which make an epidural / spinal inadvisable, such as former back surgery.
There will be quite a lot of people (eight or so) in the room. A screen is placed over your chest so that you can't see what's going on. Once the operation has begun you will feel pressure and touch, and maybe a 'rummaging' sensation in your inside, and you will hear the clinking of instruments and suction noises.
Your baby will be born within about ten minutes of the operation starting. Providing all is well, you can hold your baby while the surgeon sews you up. This takes about 40 minutes.