A dress code of smart casual requires that you look smart but not overly formal.
Men should wear a jacket or blazer and flannels or chinos, not jeans.
A shirt and tie can be worn but an open collar is also acceptable.
Women should aim to be smart in a dress or skirt and top with a jacket or smart cover-up.
Avoid sportswear and wear smart shoes, never trainers. Equally don't be too formal; hats and evening gowns will look out of place.