Put the potatoes in a large saucepan, cover with water and a lid. Place over high heat and bring to a boil. Reduce the heat and simmer for 5 minutes. Preheat the oven to 210C/190C Hot Fan/Gas 6½.
Drain the potatoes in a colander and let them sit for 5 minutes, then return them to the pan and shake vigorously to break down the potatoes and scrape the surface – this will make them much crispier when they roast.
Add 3 tablespoons of oil, season well with salt and pepper and mix. Spread the potatoes on a large baking sheet (or two smaller sheets).
Place the chicken on another baking sheet or in a roasting pan (choose a dish with sides so that the cooking juices do not run out). Cut any string from the chicken, season with salt and pepper and sprinkle with dried herbs, if using. Roast the chicken and potatoes on two racks in the oven for 20 minutes.
Place the bacon slices on a board and quarter them lengthwise to make 8 thin slices. Wrap a piece around each sausage.
Compose the stuffing with the 175 ml of just boiled water then leave to rest for 5 minutes before rolling into 8 small balls.
Take the molds out of the oven, arrange the bacon-wrapped sausages around the chicken. Flip the potatoes and add the carrots and stuffing balls in the same tray. Drizzle the remaining oil over the carrots and return both pans to the oven for another 20 minutes.
Take the molds out of the oven, turn over the vegetables and the balls of stuffing. Flip the sausages and return both trays to the oven for an additional 20 minutes, or until the chicken is cooked through and the juices run clear when the thicker parts of the breast and thigh are pierced with a skewer or the tip of a knife. (If your chicken is larger than the suggested size, it will take longer to cook.)
Transfer the chicken to a serving platter or board, cover with foil and a few tea towels to keep warm, and rest for 10-15 minutes.
Transfer roasted vegetables, stuffing balls and sausages to serving platters and keep warm. (If you turn the oven off and leave the door slightly ajar, you can keep them warm inside – and you can warm your plates and serving dishes at the same time.)
To make the sauce, mix the flour with the fat and cooking juices in the roasting pan used to cook the chicken. Stir in half the broth, using a wooden spoon or spatula to scrape up any drippings. Pour into a small saucepan, add remaining broth and simmer gently for 2-3 minutes or until thickened, stirring occasionally. Season to taste and strain into a warmed pitcher of sauce.
Put the Brussels sprouts in a microwave-safe serving dish, add 3 tablespoons of water, cover and cook on full power for 4-5 minutes or until tender. Season with salt and ground black pepper.
Place the peas in a microwave-safe serving dish, cover and microwave on high power for 4-5 minutes or until warmed through. (You can boil the sprouts and peas if you prefer.)
Carve the chicken and serve with the roasted vegetables, stuffing, sprouts, peas and sauce.