How did Miss Honey get enough food to eat?

Miss Honey filled up on school lunch.

"I most certainly have," Miss Honey said. "I pay ten pence rent, and the rest just about buys me paraffin for my stove and for my lamp, and a little milk and tea and bread and margarine. That's all I need really. As I told you, I have a jolly good tuck-in at the school lunch."