1. Prepare a medium fire in a covered grill; push hot coals to one side. Or preheat a gas grill for an indirect fire. Cut 1 lemon in quarters and stuff into chicken cavity. Use your fingers to loosen skin of chicken breast and thighs from meat. Carefully insert herbs under skin, taking care not to break skin. Rub skin with 1 tablespoon of olive oil and season with salt and pepper. Do not truss chicken.
2. Set chicken, breast side down, on grill rack away from coals. Lower hood and grill 20 minutes. Carefully turn breast side up and continue to grill, covered, until thigh juices run clear when pricked with tip of a knife, 40 to 60 minutes longer. (An instant-reading thermometer should register 180°F) Squeeze juice from remaining lemon and mix with remaining oil to brush over chicken during last 15 minutes of cooking.
3. Let chicken stand 10 minutes before carving.