Preheat the oven to 425 degrees F (220 degrees C/gas 7).
Score the skin of the pork through the fat, the incisions should be about 1 centimeter apart. Turn over. Make a pocket for the stuffing by cutting an incision at an angle, about 3 inches (7.5 centimeters) deep in the center of the streaky part of the loin, working away from the eye meat. Starting slightly in from the side of the meat, slowly slice along the loin not quite to the end, this will ensure your stuffing won't fall out.
Chop half the thyme with 1 clove of garlic and scrunch together with the butter, 1 tin of peaches, and a good pinch of salt and pepper. Push the butter into the pocket and pat back into shape. Lay the pancetta, bacon or Parma ham over the pork, leaving the skin side uncovered, and tie up firmly with 3 to 4 pieces of string.
Place skin-side up in a roasting tray with the remaining peaches, the garlic cloves, thyme, and half of the white wine. Roast for around 1 hour until the skin is crisp and golden.
When ready, remove the pork and peaches to a plate and leave to rest for 15 minutes whilst you finish the sauce. To do this, remove most of the fat from the roasting tray, then place the tray over a high heat. Squash the cooked garlic and add 1 tablespoon of flour. Stir and add the rest of the wine with a glass of water or stock. Simmer and leave to reduce for a few minutes. Strain and add any extra juices from the rested pork. Check the seasoning and consistency and serve drizzled over the sliced pork.