The food at Glyndebourne is gorgeous. You can have afternoon teas in mildmay resturant. And you can have a picnic hamper made up for you if you would like to eat in the gardens in the interval. Or you can have a buffet meal in Nether wallop, or a meal with better waitress/waiter service in middle and over wallop or in mildmay.
The service is fantastic, and the choice of wine is extensive. It is a great afternoon/evening, but with tickets to the opera, the meal and the wine, it is inevitably going to set you back a fair amount! Well worth it though. read more