Pre-heat your oven to 190C or 170C fan oven or gas 5 or 350 F.
Oil a suitable roasting tin (larger than the chicken with lifted edges to keep in the meat juice)
Prepare the garlic by peeling it, and keeping about 5-6 whole. Chop 1-2 in small pieces.
Gather zest the lemons (keep it separately) and cut the lemons in half.
Mix the butter with salt and pepper, the chopped or mashed garlic, the lemon zest and some thyme and rub it around the outside of the chicken. Lift the skin and rub the mixture in between the skin and the meat.
Stuff the chicken cavity with the halved lemons, garlic pieces, salt, pepper and the rest of the thyme.
Tie the legs with a baking twine, so that the inside stuffing won't come out during the baking.
Place on your baking tin and bake for 90 minutes before testing (if the juices run clear the chicken is done)