Don't worry about it, nobody will care! Most hunts want all the support they can get and as long as you're smartly turned out nobody will give a fig, lol. You're better off wearing one and feeling safe than worrying about not having one on. Oh, and the most important thing is to enjoy yourself!
I went out on Saturday with a wooly jumper, BP and waterproof over the top (and thank God I did cos we got SOAKED!). Agree with above, unless it's with one of the 'fashionable' packs which we def don't have in my neck of the woods sure they prefer the support to the looking 'correct'. Have fun!