Many of the resorts, but not all, have good restaurants. Outsiders are always welcomed. Prices are slightly above mainland. The cheapest feed is roughly 60 baht for a bowl of noodles. Expect to pay 80-200 baht for a main course at non high-end places (usually 100-150 baht).
If you want to cook for yourself then a small selection of fruit/vegetables is available at a stand/shop operating some distance across the bridge from Ban Klong Chao, before the Sunset Bar. Basic staples and ice cream are available at a number of shops around the Klong Chao.