Brush 1 tablespoon oil in the centre of a rimmed baking sheet slightly larger than the size of the chicken, and place the lemon slices in a single layer on top of oil. Place chicken, skin side up, on lemons. Pour over the remaining marinade from the packaging.
Roast chicken for 1 hour. Transfer chicken to a carving board, and let rest 10 minutes. Cut chicken into 8 pieces, and serve with roasted potatoes and vegetables.