BIL's. According to DH dress code is anything you want although he will probably wear his smart trousers and a shirt.
Helpful.
No idea what SIL-to-be wants the dress code to be. FIL says he will wear jeans and T-shirt (pretty sure MIL will not allow this and he will also wear a suit/shirt.)
I'm not good at stylish or elegant, more clunky and chunky. Size 10 tops, size 14 trousers, boat sized feet. Don't have any going out clothes beyond black jeans and a smart T-shirt but feel that's not enough for a wedding?