I have a Sunday night drinks and pizza hangout with friends and a jazz band. What do I wear?

I want to look smart and very casual at the same time. I get off work and only got 2 hours to prepare for the hang out. It is not a big thing but I would love to very casual yet simple, sexy and classy. I was thinking a jeans bum short and a loose t-shirt top along with gypsy sandals and busy hands with a stud or peal earrings?