That's great that you are thinking in advance about feeding your baby. 
However...can I add to the chorus of voices saying that choosing to express all feeds when you have a genuine choice just to put the baby to your breast is setting yourself up for a huge amount of hard work. When you have had a baby, you want to minimise the work, not create more work.
You are basically doubling the time taken for each feed (firstly, to express, then to feed the expressed milk). And newborns feed a lot, even directly from the breast / from a bottle with formula. Many women say that they feed that their newborn "feeds all the time". Yours will be feeding all the time, plus you will be trying to fit in the expressing / cleaning all the bottles / teats / pump etc.
You will have to do this in the night. Perhaps every 2 hours. There is no way that I would have chosen to be awake rather than asleep with a newborn.
Your DH can do soooo much. In fact everything, apart from breastfeed. For example: soothe the baby (do not underestimate how much a newborn needs soothing), wind the baby, change the baby, entertain the baby, take the baby out so you can get sleep. make all meals, do all housework.
You could perhaps express one feed a day, so that your DH can feed the baby his / her last feed of the evening. This would involve your DH, give you a rest, and still do a bit of feeding.
Pumps are far less efficient at getting the milk out than a baby is. You might find it pretty difficult to express (some women find they can only express very small amounts, whereas they are able to feed the baby direct from the breast no problem).
Many many women have gone back to work at 4 months, and moved the baby onto a bottle (with expressed milk or formula). But give yourself a break for the first 4 months, and breastfeed!