Preheat the oven to 220ºC.
Mix the butter sage, thyme, parsley and zest together with 1 tsp of salt. Place the chicken in a roasting tray and rub 1 tsp of sea salt over the skin. Then rub half the herb butter under the skin and half over the top. Cut the garlic in half and the lemon into wedges and place in the chicken.
Put the chicken in the oven and immediately turn it down to 180ºC. Roast for 1hr 30 minutes or until the juices run clear, basting the chicken every 30 minutes. Remove the chicken, cover with foil and leave it to rest for 20 minutes before eating.