The George Kerferd Hotel, the hub for the festival, is fully licenced with a great range of beers and wines including local wines.
The Arbor Bar and Restaurant serves reasonably priced meals for all tastes with vegetarian and gluten free options. They also have pizzas and inexpensive bar snacks. See their menu here: Arbor Bar and Restaurant menu
There is usually also a BBQ with sausages and steak sandwiches under the trees in the hotel grounds. And, there is also likely to be a food truck for those quick bites.
Beechworth, a short walk or drive away, has four hotels, and a wide range of restaurants and take-away outlets, including the famous Beechworth Bakery