Preheat the oven to 200°C.
Place the potatoes and carrots in a saucepan, cover with cold water and bring to the boil. Cook for 5 minutes, then drain well.
Place the sausages, onion and apple in a large roasting tin. Add the potatoes and carrots.
Spray well with low calorie cooking spray, season with a little salt and black pepper and toss around to coat the vegetables evenly.
Place in the oven and cook for 20 minutes, shaking halfway through to ensure even cooking.
In a small bowl, mix together the honey, mustard, garlic granules and apple juice. Pour over the sausages and vegetables and toss around to coat well.
Add some thyme sprigs, return to the oven and cook for a further 20 minutes, until the sausages are cooked and the vegetables are browned. Serve!