1) Buy and eat something healthy somewhere.
2) Bring a sandwich with meat, maybe some cheese, veggies, a healthy mayonnaise (olive or canola preferably) and /or mustard and/or guacamole, and a good bread (gasp).
3) Bring some pain-in-the ass Tupperware meal you have to heat up somewhere.
So you basically have it right.
I get lunch at work (I'm a dietitian, so I'm considered part of foodservice) and I go with sandwiches because I've grown to loath meals requiring a fork, knife, and heating up for lunch. Sometimes I have what they're serving to the residents/patients where I work if it's in line with my eating habits.
I go to Costco and get a shitload of Dietz and Watz ham, turkey, and Swiss Cheese in packages (very high quality cold cuts), and dozens of cans of tuna, sardines, chicken, and salmon for fish or chicken salads and sandwiches.