Heat oven to 160c/140c fan/gas3. Brush a large roasting tin all over with butter and smear some over the skin of the Carlow Free Range chicken.
Place the Carlow Free Range chicken in the tin and arrange the potatoes around it. Put the halved garlic heads in the tin, pour over the white wine and stock, then cover with foil and place in the oven. Cook for an hour and then remove the foil and give the potatoes a shake. Add the herbs and lemon wedges, and then cook uncovered for 50 mins.
Turn the heat up to 200c/180c fan/gas 6. Cook for 30 mins more, and then remove the Carlow Free Range chicken and potatoes from the pan. Cover the Carlow Free Range chicken loosely with foil and leave to rest on a plate for at least 10 mins before carving. Keep the potatoes warm. Serve with any pan juices.