Take the chicken out of the refrigerator around 30 minutes before cooking.
Preheat the oven to 190°C fan / 210°C conventional / Gas Mark 6.
Pat the chicken skin dry with kitchen paper.
Mix together the softened butter, garlic, lemon zest, Dijon mustard, honey, thyme and rosemary.
Gently loosen the skin over the chicken breasts using your fingers.
Push some of the flavoured butter underneath the skin, then rub the remaining butter all over the outside of the chicken.
Season generously with salt and black pepper.
Place the lemon halves inside the cavity.
Place the chicken breast-side up in a large roasting tin.
Pour into the roasting tray 250ml of hot chicken stock. This will help keep the chicken juicy. Use the juice to baste the chicken approx every 30 minutes.
Roast for approximately 1 hour 20 minutes–1 hour 30 minutes, depending on the size of your chicken.
Check the thickest part of the chicken with a meat thermometer. It should reach 75°C.
Remove the chicken from the oven and allow it to rest for 15–20 minutes before carving.
Add the chicken roasting juices to a saucepan over a medium heat, a little at a time, followed by a little flour. Stir well until smooth, then repeat this process 2–3 times until all the juices and flour have been incorporated. Gradually add 150ml of boiling water, stirring continuously until you have a smooth gravy. Bring to a gentle simmer and cook for 1–2 minutes, stirring regularly.
Add the Dijon mustard, Worcestershire sauce and honey. Simmer gently until the gravy has thickened.