Hey whats up man.
I know where your comming from as far as eating in school (just graduated this year) but believe me there are ways to get the food in as long as your willing to put in a little bit of effort.
As far as what to eat stick with beef, chicken, tuna, eggs, steak, whey protein powder, oats, whole wheat bread and pasta, fiber cereals, natural peanut butter, flax oil or olive oil, and nuts like almonds. You want to formulate meals so that you get in the desired amount of macro and micro nutrients (check out fitday.com to plan out what to take in to reach your calorie goals.) As far as how much that depends on your build (what are your stats?)
Now regarding meal timing that is where some effort will come in. Personally I woke up early every day so I could get my egg whites, turkey bacon, ezekiel bread, and asparagus down and although it was a chore its a neccessity. Even if your busy Im sure you could make time for a bowl of oats or fiber cereal and a whey shake or some eggs.
At school you have a lunch period and personally for me a study hall to eat again. My schedule wasnt perfect so i found myself eating tuna in the bathroom stall alot (I was anal about meal timing) and believe me it was beyond a PITA but its all worth it to get in the nutrients your body needs.
With a little work (making meals the night before or in the morning) you can et all your meals in and enough calories to grow.
