I often make extra on the night before meal and take that in
Examples include: left over stir fry, spaghetti bolognaise, an extra jacket potato with salad.
I also quite often take in homemade soups, leek and potato, vegetable, red pepper and tomato, lentil.
You could always throw things in a slow cooker (if you have one) before you go to bed and then in the morning it's ready and you could throw it in a tub and take in to work.
Quick options: mugshots are nice enough and quick in work, fruit and yogurt
Hope that helps!