Start pumping and freezing your milk, in date labelled containers, about a month before returning to work. This will enable you to stock up, to get used to your pump, and work out how long each pumping session will take. Advise your employer of your intention in writing, so that s/he can conduct a risk assessment specific to you and your breastfeeding needs. Although not a legal requirement, it is good practice for employers to provide a private and safe place to express breastmilk. It is important to store your breastmilk at the correct temperature: if there is a refrigerator available at work, be sure you label your milk with your name or keep it in a bag so it is not mistaken for cow's milk. A cool bag with ice is an alternative.
At the same time that you are preparing, your baby will need to get used to taking milk from someone other than you, and you may find it difficult to introduce a fully breastfed baby to a bottle. Often a baby will not take expressed breastmilk if his mother is nearby, so enlist the help of your partner, friend or family member to try feeding your baby with a bottle, cup, or spoon in a different environment, or while you are out of the room.
Have a practice run in advance – where your baby stays with your chosen caregiver for a few hours to give you time to iron out any problems. You could use this time to take a trip into work, or prepare your outfits and pumping equipment you will be taking with you each day. It is a good idea to have a spare top at work, just in case your breasts leak, as well as, of course, a good supply of nursing pads. Two piece outfits with lightweight tops that pull up from the bottom are most convenient for expressing.
Although leaving your baby to go back to work for the first time may be hard for you both, at least you will know that you are still providing the best nutrition for him while you are apart.