advice needed

Hi ladies My baby isn't due til June but I'm seeking advice. I would like to breastfeed but I'm not sure how demanding its going to be. So my question is: Can I express and feed the baby that way? If so how often should I express, where and how to keep the milk so I can use it later. Should I get a hand pump or an electric pump? I also don't have the best diet....no dairy, no fish no seafood. What vitamins should I take to make sure my milk is helping the little one is having the best start. Thanks