This is the sort of thing I think most people would want at the seaside.
Hot drinks: Coffee, tea, fruit/herbal teas, hot chocolate with marshmallows and sprinkles.
Cold drinks: water, fizzy drinks, flavoured water, iced coffee, iced tea, slushies.
Hot food: fish and chips, burgers, jacket potatoes, kids beige stuff, all-day breakfast, pancakes, toast, toasted sandwiches/paninis, soup with crusty bread.
Cold food: sandwiches or filled rolls or baguettes, salad, quiche, ice-cream, cakes, cookies or biscuits, chocolate bars/sweets.
If you could also offer some vegetarian or maybe vegan options in each section, that would widen the appeal.