I worked at a university when I was pregnant so I would get lunch from the refectory if I hadn't had time to make my own.
I usually ended up buying a sandwich - I stayed away from ham and other deli meats, but to be honest, I didn't worry too much about salads etc on sandwiches. They made the sandwiches up fresh after the breakfast trade ended and they were always sold out by about 1pm so they were always fairly fresh. Maybe I should have been more careful, but what else are you going to eat?? It's difficult to buy anything that doesn't fall into the 'listeria risk' category.
Oh - plus I used to CRAVE hot chips soaked in vinegar so I had a fair amount of those!! Yumm! Not very nourishing but OH so good!