Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain. In a saucepan over medium heat, combine cheddar cheese, milk, butter, cottage cheese, and sour cream; stir until melted. Pour cooked noodles into the cheese mixture and stir until well mixed. Stir in canned tuna and green peas; heat thoroughly.