Hi
I always struggle with lunches at work but here are a few ideas:
Soup in a flask
Ryvita with HEXA cheese / cottage cheese / smoked salmon
Salad with tuna / ham / cheese / pasta / new pots
Homemade falafels
I also always have a draw full of low syn crisps, hifi light bars, mug shots and a good supply of fruit and yogurts. Invest in a cool bag and a food flask as well then you can take left over tea which will stay warm and your yogurts will stay cold!
There is a lunches thread on here which gives some great ideas too.