Roast 2 cups of the cherry tomatoes according to this recipe. These can be made in advance and stored in the fridge for a few days.
Cook the couscous according to the package directions until al dente, about 9 minutes. Drain and set aside to cool.
In the bottom of a large bowl, whisk together the olive oil, lemon juice, garlic, thyme leaves, salt, and several grinds of pepper. Add the cooled couscous and toss. Slice the remaining raw cherry tomatoes in half and add them to the bowl along with the roasted tomatoes, the chickpeas, basil, cucumbers, and feta. Top with more thyme and basil and a generous drizzle of olive oil. Season to taste and serve.
