T.R.
My recommendation is to skip the meal plan. First of all, what I found online is that it includes an entree, a snack & a drink. Only 1 drink.
My hubby & I went to Universal in Florida a year ago (Nov '12). Great theme parks, you will have a ton of fun!!
I found some info for you regarding food, see these links:
https://www.universalorlando.com/Images/Mythos%20Menu%205...
Mythos Restaurant menu with prices - this is the "fine dining" restaurant in Islands of Adventure
https://www.universalorlando.com/Resort-Information/What-...
Carry-in guidelines - drinks & snacks are OK.
http://www.orlandoinformer.com/2013/visiting-universal-or...
The Low-down on park policies - more details about carry-ins
http://www.orlandoinformer.com/universal/three-broomstick...
Three Broomsticks menu & prices - we LOVED the food here!
Based on just the 3 Brooms menu prices, it looks like you & your daughter can have a meal there for easily under $20/person. FYI, we both prefered the pumpkin juice over the butterbeer. And don't waste your money on the "refillable mug" for the butterbeer, you still need to pay for the refills, & it is a pain in the arse to carry around.
You can bring in drinks, snacks (fruit, veggie, etc. some people get away with sandwiches, no guarantee. see policies & make a judgement call). My advice is to eat a hearty breakfast, bring a small snack, & plan for a nice dinner later.
I don't know what your itinerary is for your stay in Florida - we bought a 3-day hopper pass for Universal. That gave us one day each in Univ. Studios & Islands of Adventure, & then the 3rd day to go back to one for 2nds... we loved Islands, that's where the Harry Potter park is.
There is also mini golfing after hours in the City Walk (along with a number of fine & casual dining restaurants). They have black-light, & 2 themes, either Sci-Fi or Horror. We had a blast doing that (& taking pictures @ every hole!)
When you are waiting in line for rides, if there is an option to "ride single", TAKE IT! They use individual people to fill up rides that seat 4 or 6, but have empties when groups of 3 or 5 are in line. It's not like you & your daughter are going to talk while the ride is going, & we were able to ride the Harry Potter "Forbidden Journey" 3 times in 45 minutes (the wait time for the normal line)
Also, the Men In Black ride is a DO NOT MISS! You get to shoot the aliens
In short, go & have a ton of fun. We tend to not spend much $$ on theme park food, but there are some good places if you want the experience. T. =-)