Preheat oven to 350 degrees. Slice the bread in half lengthwise. Use the bottom, wrap the top of the loaf in plastic wrap and save or freeze for another meal.
Drizzle some good fruity olive oil on top the bread. Put in the oven until lightly toasted, about 10 minutes. Pull the bread out of the oven and rub with half a garlic head.
In a medium bowl, cream the goat cheese with milk to make the consistency lighter and more spreadable.
Put the tomatoes in a bowl, add the herbs, shallot, and season with salt, pepper and a drizzle of white balsamic vinegar. Gently toss to combine.
Pan grill the pancetta until it is on the softer side of crisp. Set aside on paper towels, to drain off the surface fat.
Spread a thin layer of cheese across the loaf. Lay the pancetta evenly across the cheese, and lay the tomato slices on top of the pancetta. Top with baby arugula leaves. Finish with a drizzle of olive oil and a fine grating of lemon zest over the top. Slice on the diagonal into single servings.