i suggest you go to the ABA (australian breastfeeding association) website for lots of info.
you will probably need to express at the times you are not with your baby when you would usually feed to keep comfortable.im quite sure legally your work place HAS to provide somewhere comfortable for you to do this (not a toilet!!) and a fridge to store milk in.
i guess thats why some people wean to formula as it is more work to express but if you educate yourself on breastmilk you may be more determined than if you dont!:P
breasts work on supply equals demand so you will produce what is taken out. the more you feed the more milk you make. so you would probably need to express a little bit to keep your supply up.