Associate
Very sorry for your loss, if my limited experience of funerals is any help - I don't think you'll remember what you wore looking back on it, or care what anyone else thought about what your wore. It's very cold at the moment here, so you could probably go with smart black trousers, white shirt and a dark tie - along with a big warm coat to wear while you do all the outside standing around. Hope you're OK, keep the happy memories front and centre.