Heat the grill to high. In a shallow bowl, whisk together the eggs, lactose free milk, cheese and chives. Heat some oil in a large non-stick pan over a medium heat.
Dip slices of gluten free bread into the egg mixture, then place them in the pan. Cook for 3-5 mins on each side, or until golden and crisp, then keep warm in a low oven if you need to.
Place the vine tomatoes on a baking tray, drizzle with a little oil and season with salt and pepper. Grill until they start to soften and blister. On a large platter, pile up the cheesy French bread, grilled tomatoes, sliced ham and a pile of watercress, and let everyone dig in.