The opening hours of the City Record Library are the same as those of the library. If you're a good cook, you can try to cook your meals yourself. Most student houses have a common kitchen where you can prepare your own dishes. Although you can save money by making your own meals, you will miss great opportunities to meet other new students than your housemates. Another disadvantage is that you risk not bringing enough variation in your food.
Most people buy their ingredients in supermarkets.
The little private groceries still exist, but they are usually more expensive. There are also plenty of small Bakeries and Butchers in Leuven. Most of the time they are also more expensive. You won't easily find other cities where you can find more possibilities for eating out. Let's only mention the cheapest ones here.