My suggestion is along the line of Suz's suggestion: Have a vegan type of bread in addition to the croissants (e.g. a vegan whole wheat or rye), and a vegan spread such as mustard so that any vegetarians or vegans in your crowd can get fed with a veggie sandwich. Include some additional sandwich fixin's such as cucumbers, lettuce, onions, etc. Or have those sandwiches available as pre-made options. You might also want to consider salad with several choices of dressing (at least one of the choices being vegan).
Overall, your menu is simple and uncomplicated, yet difficult for vegetarians and vegans, and high fat. The vegan options would take care any vegetarians in the crowd, as well as those wishing to eat lower in fat than ham, cheese, chicken salad and croissants.
I also recommend adding water, definitely plain bottled or filtered, and perhaps sparkling to your beverage line up.