Cheese pizza is acceptable to vegetarian and meat eaters alike. Barring a disproportionately vegetarian crowd, most groups would be perfectly happy with 50% cheese pizza and 25% each veggie or meat combo/pepperoni. The less sure you are about people's dietary preferences, the higher you crank the cheese %.

If it turns out there's a huge population of like gluten free, you say "Ah my bad" and correct the next time.