1st job interview since the DCs - what to wear?

[TruthSweet]

It's not for the CEO of a bank (it's Argos actually) but I haven't a clue what to wear. I've got a black trouser suit and a pale pink boucle skirt suit left over from my office days and one pair of smart black trousers but I'm not sure what the done thing is these days (my last job interview was in 2001).

I'm 30, tallish and a 16/18.

Oh and do I wear my hair up or down?

Black trouser suit sounds great, doesn't matter about the hair as long as its neat.
Good luck!

Black suit never dates, team it with a plain cami/top underneath and a pretty necklace.