I dont think its nesasary to take in loads of stuff if your planning on a normal vaginal delivery, just make sure that your OH knows where stuff is like baby clothes, nappies, your clothes, underware, towels, etc are, that way if you do end up staying longer than planned etc they can just bring anything you need in with them when they visit, saves you packing everything including the kitchen sink! Last time I ended up in hospital for 3 days so I just wrote lists each day of bits and pieces that I wanted OH to bring in with him and he took away dirty clothes etc with him each day.
Helen you will prob need to pack quite a lot as you have two babies to contend with, and if your going to be having a section you will certianly be in for a few days so be sure to have enough clean underware and nightware etc, and loads and loads of maternety pads!