Have a read of the Exclusive Expresser's thread, (if you haven't already).

It is certainly do-able, but as mentioned, it is loads more work. It makes leaving the house fairly difficult, in the beginning. Supply can suffer sometimes, the pump is not always as efficient as bub at drawing milk from the breast. And HotI mentioned the antibodies and less sterility (although on both counts, there are still benefits that you don't get with formula).

I've formula fed, and breastfed and EE for 14 months. If I had my time over I would have persisted longer with bfing. Having said that, I know when I made the decision to stop trying to bf and EE instead, I was at the end of my rope.

I wish you the best with whatever you decide to do