I do have a fridge where I work but here are a few ideas you could adapt. I buy those little cans of snack size tuna - they come with or without crackers and come in a few flavours such as tuna with lemon, with cracked black pepper, sundried tomatoes or low fat mayo (my favourite). There are also little cans of salmon, but I only like tuna. There is a pull tab to open it. You could take that plus some fruit and a single can of V-8 juice. Or what about freezing an icepack the day before or some icecubes in a ziploc bag and then taking cutup vegetables or some yogurt. Good luck. Hope this helps. You could also take some wasa crackers for the tuna.
PS. I always try to eat some kind of protein at lunch.