NBB has it's own canteen. To access it, either walk to the 3rd floor G-kitchen and take the skywalk, then the elevator down to the cantina, or walk to the G-kitchen, take the elevator/stairs to floor -1 and walk through the corridor to your left.

The H.C. Ørsted Institute and the Biocenter also have canteens that are within walking distance from NBB.

If you feel like eating out, there's several options nearby. At Stefano's Pita Guys you can build your own pita or you could go to Køkkenet and try one of their roasted pork sandwiches.