DH and I have been invited to one of his colleagues' houses on NYE. They're pretty wealthy and successful - he's an academic, she's a high flying lawyer. I'm fairly comfortable with my slightly edgy school run clothes but so rarely go out my most recent 'going out' dress is 7 years old. I'd love to look cool and sexy in an understated way - any genius advice? I'm late 30s, size 10, quite conscious of my tummy after two whopper babies. Any suggestions would be welcome!