There's a foodcourt at CityGate if you stay at Novotel, but probably won't be open till 10-11am. But probably still open the night you guys land. And a McDonald inside the mall.

Otherwise, you can eat when you get to the airport. More choices at T2. Or after you go airside. The price aren't that unreasonable, especially when you compare to the cost of hotel breakfasts.

If you're on a budget, I assume you can find some AirBnB in the Tung Chung area where Novotel is.