The only thing Captain Cook's has is desserts and drinks, so you're out of luck there.
Unless there is a grab n go somewhere at The Poly that has some of the small hummus, salads type things, you won't be getting anything meal worthy with snack credits. If you want to hop on the monorail, Contempo Café and Gasparilla Grill both have that type of snack items for a snack credit.