Just in case anyone else finds themselves in the situation of needing a low calorie dominos pizza, I have found a solution!
If you order a small pizza and then, in the customise section, swap the base to an Italian base, and swap the cheese to “delight low-fat” cheese, the calories aren’t bad at all. The one I ordered (Hawaiian) was 399 calories for the whole thing! Obviously not the healthiest thing in the world but saves a few calories and saves being the one friend not ordering pizza! Plus you really can’t tell the difference between the low-fat cheese and I personally think the crust is actually nicer!