Apart from rates to the council, energy costs, rent, employee wages, insurance, cleaning and maintenance costs you are right of course.
Hey if you are happy to pay 7euro for tea and toast all power to you. I'm sure the establishment that charged will be more than happy with your contribution to their maintenance costs.
I'm inclined to think however that if a Cafe or Restaurant is relying on the inflated margin they are making on basic goods like tea and toast then they obviously aren't selling enough of what they should be ie. prepared meals.
I applaud your charity though, but personally I'll be keeping my 7euro.