Does it have to be macaroni cheese? If so, I think you need to nip next door and borrow some flour, marg and milk to make your sauce. Why not just boil the macaroni and grate cheese on top? If it's only for yourself, it doesn't have to be fancy and will fill a hole.
i really just need to know amounts i need to use with the ingredients i listed as a friends mum lived in barbados and cooked it for us and it tasted lovely and those were the only ingredients used it was more like maccaroni pie as it didn't have a sauce
For one person.
Boil one beaker-ful of dry macaroni until soft in a non-stick saucepan. Drain and return to the pan. Add 2 or 3 oz of strong grated cheddar cheese. When it starts to melt, add a good squirt of tomato ketchup (or tomato purree) and either a small teaspoon of mustard powder or liquid mustard. Stir well until all mixed up. Serve and sprinkle with paprika for garnish. This is a fairly dry mixture as the only liquid will be the melted cheese coating the macaroni.