Hi Whitevanman,
Don't worry - your question, and your problem looking for some variety in your lunches, is a perfectly valid one and a problem that I suspect a lot of people have. One thing I have done in the past is to prepare a pasta salad the night before, something like penne pasta or spirals, some bits of shredded chicken, some chopped peppers and onion, add a coating of a salad dressing (could be a spicy dressing or something more bland), mix the whole lot together and you end up with something you would pay around £4 in a supermarket, but at a fraction of that cost. Instead of chicken you could use some leftover cold roast meat, ham, chopped bacon, cold sausages sliced, etc. As you said, keeping it cool during the day isn't a problem for you.
If the pasta is too high in carbs for you, then you could try Dreamfields pasta, as that has only 6 grams carb per portion. In fact you might find that making it with Dreamfields is actually too low in carbs, but you could always have some fruit for dessert which would push up the total carbs for the meal. The other problem with Dreamfields can be getting hold of it as they don't have many retail outlets and its expensive to buy direct from them online.