You can use a large loaf of French bread or Italian bread or a long baguette.
If you don't have any pizza sauce, a jarred marinara will work as well!
If you slice your veggies thin or chop them up fairly small, it shouldn't be a problem to add them raw. If you like your vegetables on the thicker side, I would recommend giving them a quick saute in a skillet so they have more of a chance to cook through in the 8-12 minute bake window.
Mozzarella cheese is the most melty, but feel free to play around with your favorite varieties.
To make it absolutely amazing, I like to brush my bread with garlic butter first.
If you like your crust extra toasty rather than soft, pop it in the oven while you gather your pizza toppings.