You can have a look at our Cost of Living in Denmark page - it includes a cost of living table which was updated last month so the information should be relatively current. I can also recommend Numbeo and Expatistan, both of which you'll be able to find easily by Googling. These are two cost of living databases that constantly gather figures, and they're both very extensive. You can draw up a mock budget using these figures. For instance, the prices of individual grocery items like milk, bread, chicken breasts etc, are listed. By estimating what items (and how much of them) you buy in a month, you can get an idea of monthly food costs.
Hope this helps.