In the cafeteria or in the small coffee shop.
desayunas en casa o en la cafeteria means breakfasts in house or in the cafeteria
It means "When are you going to the cafeteria?"
How do I answer this question
In my school cafeteria
It means, "Do you [all] eat in the school cafeteria?" It uses the polite form of 'you all.'
Do you eat a pizza in the cafeteria?
la cafetería
A cantina can be any establishment like a canteen, snack bar or cafeteria, but mainly it means bar.
Où est le café means "Where is the cafe?"Notice that I changed your "la" to "le". This is because café is a masculine noun.
Se come en la cafetería
cafetería