Preheat the oven to 220°C/gas mark 7. Cut the peaches in half, remove the stones and cut each half into slices.
Brush the peach pieces with the oil. Heat a griddle pan over a high heat and place the peach pieces on it (you might need to do this in two batches). Cook on each side for 1-2 minutes, until there are dark brown griddle marks on each side. Set these aside.
Divide the slices of mozzarella between the two pizza bases. Top this with the Parma ham (you can lightly tear this to distribute it more evenly) and peaches.
Place in the oven and cook for 10-12 minutes or until the cheese is golden brown and melted. Divide the rocket between the pizzas and serve.