I bought a dress (in Asda of all places!) that I'm really happy with and since it was so cheap I thought I would share the bargain.
navy jersey £16
I even went back and bought the pink one, too. 
It's not a maternity dress, but the ruching flatters the bump, and it's a nice length. I'm 5'6'' and the normal length one hits right in the middle of my knee. It runs big ? I'm normally a 14, but I bought a 12 and am 32wks (though relatively small bump).
Here's hoping I can breastfeed in it!