Ok so out of the blue dd has been asked to take my friends hunter in ridden racehorse at the big upcoming local show. It is just for fun really but my friend can get a bit snobby about showing so I don't want to let her down by getting it wrong 
What should dd be wearing ideally and what wouild we "get away with" if we were pushed. I don't have the money to go out for new jackets etc for one class but may be able to borrow some bits and pieces if our stuff is not suitable.
I don't generally have anything to do with TBs so this is totally out of my comfort zone! Thank you in advance for any ideas or thoughts (oh, dd is under 16 if that is important)