An hour before you are planning to cook the chicken, remove it from the brine and transfer to a paper towel-lined plate or tray and pat dry.
Preheat oven to 425 degrees Fahrenheit with the rack set in the center position.
Mix the oregano, thyme, salt, peppercorns, and lemon zest together and set aside. The moisture from the lemon zest will make the spice mixture clumpy. Use your fingers to rub and mix the spices and lemon zest together until well blended.
Mix 2 tablespoons of the spice mixture into the potatoes and chickpeas in a bowl along with the melted butter. Set aside.
Lightly rub and massage the rest of the spice mixture onto both sides of the chicken.
Put the lemon slices in the cavity of the chicken and use kitchen twine to truss the chicken*.
Place a large ovenproof skillet over high heat. Add the olive oil and heat until it is hot and shimmering.
Place the chicken, breast-side up in the center of the pan. Place the seasoned potatoes and chickpeas around the chicken.
Transfer to the back of the oven, rotating the pan until the legs are pointing to the back left corner.
Cook for 20 minutes. When the chicken has started to brown reduce heat to 400. Cook for 10 more minutes.
Take the skillet out of the oven and give the potatoes a stir. Place the skillet to the back of the oven, this time with the legs pointing to the back right corner. Cook for 30 minutes, stirring the potatoes and chickpeas halfway through. Depending on the size of your chicken, more time might be needed.
The chicken should be brown all over and the juice should run clear when you insert a knife between the leg and thigh. You can check the internal temperature in the innermost part of the thigh, the innermost part of the wing, and the thickest part of the breast. The thermometer should read 165 degrees F.
Once the chicken is done, remove it to a platter or cutting board and let it rest for 10 minutes before carving and serving.
While the chicken rests, remove the potatoes and chickpeas from the skillet and transfer to a serving bowl. Toss with 2 ounces (a 1/2 cup) crumbled feta.
Serve the potatoes and chickpeas with some arugula for some green alongside the carved chicken.