How much is food on the Ferry to France(Calais Dover).?

can i just have an average- drinks, sandwiches etc….

What Is The Best Car Ferry Between England And France?

And/or what are the best booking sites? There seem to be loads of ferries between Dover/Folkestone and Calais/Boulogne/Dunkirk, and even more sites on which to book them. I don’t care so much about the route, I really just want to find the cheapest ferry.