Hi Emma,
Other than M&M and Youngstock in hand classes , some shows hold best condition or best turned out classes in hand. In the past , I've taken youngsters in hand into the Handy Pony classes for the experience.
A white halter would be best for a native yearling. As she gets older , she could wear the white halter or an in hand bridle. You can buy leather "filly slips" for showing. It looks more like a bridle but is used without a bit although they look better on finer horses/ponies than on natives. I bitted my pony when she started cutting her first adult teeth as she was chewing everything she could get hold of. She went to her first shows at 3yo wearing an in hand bridle with a straight bar nylon bit. The lead rein has a 3 way coupling , fastening to the bit on either side and also the back of the noseband. That takes a bit of pressure of a young pony's mouth.
For yourself , a tweed jacket , shirt and tie , Chino type trousers, comfortable shoes/boots you can run in (jodhpur boots are ideal), a hat , gloves and a show cane. If you have long hair , wear it tied back or in a hairnet.
Good luck , have fun and can we see piccys pleeeease ?
