Honey-Brined Turkey with Giblet Cream Gravy

Line extra-large stockpot with heavy large plastic bag (about 30-gallon capacity). Rinse turkey; place in plastic bag. Stir 8 quarts water, 2 cups coarse salt and 1 cup honey in large pot until salt and honey dissolve. Add 1 bunch fresh thyme, peeled garlic cloves and black pepper. Pour brine over turkey. Gather plastic bag tightly around turkey so that bird is covered with brine; seal plastic bag. Refrigerate pot with turkey in brine at least 12 hours and up to 18 hours. Position rack in bottom third of oven and preheat to 350 °F. Drain turkey well; discard brine. Pat turkey dry inside and out. Squeeze juice from lemon halves into main cavity. Add lemon rinds and remaining 1 bunch fresh thyme to main cavity. Tuck wings under turkey; tie legs together loosely to hold shape. Place turkey on rack set in large roasting pan. Rub turkey all over with 2 tablespoons olive oil. Roast turkey 1 hour. Baste turkey with 1 cup chicken broth. Continue to roast until turkey is deep brown and thermometer inserted into thickest part of thigh registers 180 °F, basting with 1 cup chicken broth every 30 minutes and covering loosely with foil if turkey is browning too quickly, about 2 1/2 hours longer. Transfer turkey to platter. Tent turkey loosely with foil and let stand 30 minutes. Pour pan juices into large glass measuring cup. Spoon off fat; reserve juices.