We were at WDW last November, so I really hope things have changed for the better since then.
I would not bother with Story Book Dining, Salf777. I highly doubt that they could do plain fish and salad for your wife. Furthermore, would you really want to pay $60 for that if they even can? They won't adjust the price if that's all she can eat. They may offer fresh fruit as a salad or dessert since there is a fruit and cheese item, but that would likely be the only modification.
Since there is grilled fish on the kids A-F menu, they may be able to do that for her in an adult portion. However, I don't see any greens or salad mixture offered.
I'm gluten and dairy intolerant and found very few places that could give me anything much unless there was a g-f/d-f dish on the allergy-friendly menu that appealed. Few menus had more than salad suitable for both.
Plus, I was told at several places that they had no raw ingredients to make anything special for me as used to be fairly common. Dishes were all "pre-prepared" is what I was told so couldn't be easily altered by leaving off a dairy-laden sauce, for instance. If something on the A-F menu wasn't adaptable, I was stuck with salad or maybe a plain chicken breast or fish, but only if either of those was on the kids menu. If not listed on any menu, they said they couldn't fix something different.
As I said, possibly supplies are more plentiful than they were in November and you will have far better luck than we did.
I was very disappointed by many TS places that formerly had been wonderful. The days of chefs offering to create something I'd enjoy were sadly gone.