Being a UNESCO World Heritage Park in China does not mean it is fully decked out for non-Chinese visitors. There is a centrally located, sort of a HQ area with a restaurant serving buffet lunch. Typically Chinese stir-fry dishes. At the entrance, there is a Chinese fast food outlet serving fried chicken, and vendors selling ramen and other types of instant noodles.
A one-day stock of muesli bars and a flask of tea or coffee would help, especially if you plan to take in all the heavenly sights on foot, through the wooden planked pathways. In autumn and spring, the temperature is suitable for resting along the wooden plank path while having a nice warm drink while you wait for the lighting to be just right for your next photo shoot.
note - the food and drink in the Reserve is very expensive dish of rice about ¥30, noodles ¥15, Small bottle of water ¥5 so it's a good idea to obtain supplies in the shops outside before you enter.
