Cook the rice following pack instructions. Meanwhile, heat oven to 200C/180C fan/gas 6. Place the carrots and grapes on a large baking tray, keeping the grapes at one end and the carrots at the other (the grapes will bleed some of their juice onto the tray, which will stain the carrots).
Drizzle the carrots with the oil and season. Roast for 10 mins, then remove from the oven and set aside to cool a little. When the rice is cooked, drain and run under the cold tap to cool a little, then set aside to drain completely.
Bring a saucepan of water to the boil, add the beans and cook for 2 mins or until just tender. Drain and set aside to cool a little. In a large bowl, whisk the dressing ingredients together with some seasoning.
Add the rice, carrots, beans, rocket and half the feta, and toss everything together. Transfer to a serving plate, then scatter over the remaining feta and the roasted grapes. Drizzle any juice from the baking tray over the salad and serve.