In a small bowl combine the lemon zest, thyme, rosemary and salt.
Drizzle 2 tablespoons olive oil on a rimmed baking sheet. Lay the lemon slices in the olive oil down the middle of the tray as a "rack" for the chicken. Sprinkle one-third of the salt rub on the underside of the chicken. Turn the chicken over and rub the remaining salt mixture over and under the skin of the whole chicken. Lay the chicken, skin side up, on the bed of lemons and drizzle with the remaining 2 tablespoons of olive oil. Roast, basting every 15 minutes, until golden brown and an instant read thermometer read 160 degrees F in the thigh, 40 to 45 minutes. Transfer the chicken to a cutting board and allow to rest for 10 minutes before carving.
Meanwhile, using a fork, mash the lemon pulp into the juices on the baking sheet, discarding the rind. Mix the pulp into the drippings and use this mixture to spoon over the chicken just before serving.
The lemons used for slicing should be the same lemons you removed the zest from.