A good pair of balck stretchy pants with a fold-over waistband is a must! I wore mine almost every day to work and on weekends - dress them up with a shirt and jacket or down with a t-shirt. They wash and dry quickly and don't need ironing. I also wore them for a few months post-birth.

Then you will probably need a few t-shirts, shirts and singlet tops as well as a light skirt and sundress for warmer weather.
I got a couple of pairs of these pants from big w for like $15-20 each. They were fantastic and i wore them everyday to work