This is a great question! When I went to school, I was young, and didn't pay attention to nutrition. I ate way too many burgers! I still am not all that into nutrition. But, I wanted to let you know about waffles. Yes. Waffles. There is a high protein pancake/flapjack mix on the market that includes a waffle recipe. You can increase the protein content using milk and eggs. I make a big batch on Sunday. It takes me an hour to make enough waffles to last me the week. I freeze them. Grab one, toast it, put some jam on it (there 's a blueberry & cherry one that is really good!), and, if I am careful (lol!) can eat this on the run! I actually find myself eating these for dinner more so than for breakfast.
There are also protein shakes. I also like toasted peanut butter/banana sandwiches. Made on a whole grain bread, with old -fashioned peanut butter (the only ingredient is peanuts!), they are pretty nutritional. However, they pack a lot of calories, so watch out for that. Pretzels make a good snack. There are a lot of protein bars available, which, you can find on sale for about $1.50 each. Drinks? I bought a water purifier for my counter top, and drink tap water. Drinks have gotten outrageously expensive!
Watch out for the quick rush pick-me-upper of soda and candy bar. While they work for the moment, the brain crashes when they wear off. My favorite snack, at home, is a mozzarella cheese stick placed on top of a dill pickle stacker slice! Try it!
Hope something here has helped!