Would a cardigan be an acceptable alternative? Sensible mid blue coloured one? Thin material not big long boyfriend style one.
I'd be wearing the black suit skirt, tights, smart shoes, scarf (thin type, not wooly), hair and make up all done just the cardigan instead of the jacket.
It's actually an informal chat (which is never really informal) for a work placement in a science based industry so no fashionistas.