You should be having the salad with the jacket potato.
The deal with the 1/3 superfree is so that it limits the amount of food you eat by filling you up with lower energy density foods.
If you had the fruit salad after the JP then it would have done nothing to limit the free food you ate in the main meal - you could, however, eat the fruit salad BEFORE your JP, and then give yourself a smaller portion of the chilli and potato?