Roll out the pastry on a baking tray according to the instructions on the pack and spread the tomato puree mixture evenly on top. Wash the tomatoes, cut into slices and distribute over the pizza. Cut the mozzarella into slices and also distribute over the pizza. Season with salt and pepper and pop in the oven. When the pizza is cooked, distribute the rocket over the pizza and perhaps drizzle on a little more olive oil.