Put the feta in a shallow dish, squeeze over the lemon juice and scatter over the garlic. Leave to marinate while you prepare the rest of the salad.
Toast the almonds under a medium grill until lightly browned, then leave to cool. Cut the pomegranate in half and pop the seeds out into a bowl by bashing the skin with a spoon.
Toss together the rocket, spinach and watercress in a large salad bowl with the olive oil, and salt and freshly ground pepper. Crumble in the marinated feta, and scatter the pomegranate seeds and toasted almonds over. Serve immediately.