Ummm weddings held on farms can still be uber stylish and formal affairs, it ain't all dust and snakes Few stereotypes kicking about here LOL. I highly doubt you will be traipsing across paddocks and just because it is on a farm doesn't mean it is a hoedown LOL. Definitely ask your cousin first, because you don't want to turn up wearing jeans and a check shirt if everyone else is wearing ****tail or formal dress. But avoid high heels if you can. It will probably be under a marquee, but it probably wont have a hard floor in it.