Last night on my way home I dropped into Top Shop and ended up buying a few things. Midi lengths can be hard to pull off, the cut off point must be right for you and it totally depends on your height. For me roughly 10cm above the ankle is the most flattering point. I would suggest you stand in front of the mirror and see what works for you. The right shoe is also crucial, I think midi needs a bit of "rock edge" shoe, in my case heels are out of question so a black leather flat strappy sandal is ideal. Mine are from Office (last season) but Top Shop also does very similar style.
Zara parka, Top Shop maternity dress, Office sandals, YSL bag, Aurelia earrings, Miu Miu bracelet