Aye, in short if you can cut down a bit on the carbohydrates, especially the fast ones (sugar and refined starches), you could perhaps get a bit better control and avoid the spikes after meals a bit more and reduce the amount of insulin you take slightly. Less CPs, less insulin.
If you have time in your lunch break to go for a quick stroll, that might also help a bit along with the gym, obviously.
If you know how many carbohydrates you eat now, you could try and cut out the 20 percent you find you need the least. The chocolate would be a good place to start - even replacing it with fresh fruit in your example would be brilliant especially apples, berries and not bananas
or you could chop up a few veggies and bring with you. You can try how your body deals with raw carrots - they keep well in a plastic bag with a spoonful of water from the fridge in the morning.
Try browner versions of bread, pasta, rice when you have them - they release a bit slower into the blood stream, too.
If you can get away with eating as many colours as possible also in a meal (avoiding smarties, heh), but 2 colours of pepper, tomato, carrot... you might find your eyes also tell you sooner when you're full.
Good luck