Pizza on the grill is super easy. Before I got the pizza attachments, I would pre cook the dough. Stretch it out and throw on hot grill for 3 minutes, flip and cook 1 min. Then put your sauce and toppings on. Cook until ready. I just kept the dials on high.
Once you get a few good pies, then experiment with making your own dough, sauce, toppings etc. then buy peels!
Without a pizza stone, I would stick with "flatbread" recipes over 'pizza' recipes.