My first instinct is to go for the suit and funky top, but think if the said top flashes boobs or is inappropriate (or looks cheap) then best to opt for formal top. But then the trousers and tunic option also sounds good....sorry I'm really not much help - think I have pregnancy brain.
Ok - how about some tailored well cut trousers with tunic top, maybe layered with fashionable jacket (either swing jacket, bracelet sleeves etc or bell sleeves, kimono style belted - topshop have a really nice black wool one but would it go againsy you to be wearing topshop???!! AND I am forgetting your interview is tomorrow, not like you have time to wonder off shopping!)
I used to work for Wallis, if I rememeber I wore a suit with top for my interview.
I would dress it up with some accs, and go from there.
Oh my suits are always trouser suits and always wear heels (but could be as im only 5ft)