The contents sound fine (quaver's are probably the least inoffensive of crisps, she could have) but the quantity does seem on the low side. Then again, you know what she's likely to eat. You could add a little pot of hummus with veg and breadsticks, maybe?
My year 3 child has just gone onto packed lunch (he wants it rather than school lunch) and I'm still trying to find the correct portion sizes. I'm worried I won't give him enough.
Last year I worked in his school and was horrified at what some of the children got for packed lunch. Think cold fast food, daily. Dominoes pizza. Cold chips and deep fried chicken. Cold takeaway burgers. Sausage rolls accompanied purely by other beige food. It was horrible. I have to wonder if their parents have ever tried to eat a cold chip.
As a comparison for portion sizes, my very slight, but tall 7yo had:
Wednesday, a cream cheese bagel, a small slice of brie, red pepper, cherry tomatoes, cucumber, a handful of crisps and some grapes. He left most of the crisps and the cucumber.
Yesterday he had a blue cheese bagel, with watercress, veggies (as above), olives, strawberries, blueberries and a frube. He left loads.
Today he had hummus, pitta and veggies, grapes, yoghurt and jelly. He ate everything.
Next week I'm going to try pasta pesto and possibly a rice salad...although I'm sure he'd live on bagels and pitta bread if I let him. I worry a bit about the fat content, but he's trying to eat vegetarian for most of his meals, and loves cheese.
I'd go in and ask the school what their meaning is behind the note. It's really unhelpful of them to send it without any actual advice. My guess is it'll have been thought to not be enough (for the average child her age).