Preheat the oven to 180°C, fan 160°C, gas 4.
Chop the lemons and put into the turkey’s body cavity. Tie the sage, parsley and bay leaves together in a bunch and add to the cavity. Secure the skin over the cavity with a fine skewer.
Weigh the bird and calculate the cooking time, allowing 20 minutes per kg, plus 90 minutes (a 3.5kg turkey will need to cook for about 2 hours 40 minutes).
Pour 300ml water into a large roasting tin and place a rack in or over the tin. Rest the turkey on the rack and spread 25g butter over the breast and legs. Cover the bird with foil and roast in the oven for the calculated cooking time, uncovering for the last 30 minutes to brown the skin. To check it is fully cooked, push a skewer into the thickest part of one of the legs. If the juices run clear, it is ready to eat. If there are any traces of pink in the meat, return to the oven for a further 15 minutes or until the juices are clear. Lift the cooked turkey onto a carving board, cover with foil and leave to rest for 30 minutes.
Meanwhile, make up the stuffing according to the pack instructions. Roll into 8 balls, place on a greased baking tray and bake in the oven for 15 minutes.
Slice the turkey and serve with the stuffing, roast potatoes and the vegetables and sauces of your choice.