Sometimes I will do a small tin of tuna or salmon, rice noodles, frozen mixed vegies and a diet friendly dressing of some sort. Or you can get the flavoured tunas, not sure of the nutritional content though. I lived on that during the two weeks off work I had at Christmas.
I also make a full family size meal packed with vegies once a week and freeze it in individual portions and take it to work.
The protein shake I have for breakfast is just a run of the mill low carb protein powder, some LSA mix, banana or berries, natural yoghurt and skim milk. Mix it up with a stick blender. High in fibre too.