You cant claim DLA for food, but if you are entitled to DLA because your child has needs beyond those of a equivalent age child then you can use that DLA money to buy food.
Also none of those things are what I would think of as a necessary part of someone's diet except the rice the rice.
Sometimes it is worth being brutal and assessing if stuff you are buying is even a necessary part of your diet.
When DS has become fixated on a specific food that really isnt necessary, I have a tendency to stop buying it altogether (chicken soup) . Mayo, isnt actually a necessary part of your diet so I wouldn't bother buying it, same with the beans and crumpets. Beans are awful for texture sensitive people.
But that begs the question how is she with stuff that is necessary. EG veg, things like sweetcorn broccoli etc. Plain meat? Do you boil or steam veg? (Undercooked steam is often easiest to get a pass on) We tend to think of meat, potatoes/pasta and steam veg as relatively boring especially if eaten every day but there isnt really much wrong with it and its cheap. They dont mix easily on a plate which helps. Most of the restricted diet people (adults and kids) i know will actually quite happily eat plain meat and carbohydrates. The veg is more challenging.
Definitely get plates with separators to keep food apart. Make sure you can see everything on the plate too, nothing burried. Serve pasta sauce seperate from the pasta dont serve gravy
How is she with things like full fat milk, proper butter and peanut butter? These are all foods that can be added in to increase calorie intake if she is a bit low calorie wise. Milk and peanut butter are also handy for keeping protein levels up too.
On the rice front is it just that type of rice or is it that if it comes out the packet it's not mixed with anything. Eg DD will happily eat plain rice but is having trouble with mushrooms atm (she can tell when the mushrooms supplier has changed by texture). I'm just wondering if it as much as anything is the reassurance that the rice wont be mixed with anything.