No, you dont have anything that shows us how many percentage of fasting children (!) in the UK are doing it voluntarily.
None of these things (Which are mostly not secured yet) are about children but adults.
"It’s all about continuous hydration, where your child should be drinking at least 8 ounces of water during and after their activities, and consistently sipping throughout the day.
The body needs constant replenishment."
http://www.sensorystreet.com/uploads/Water_Water_Everywhere.pdf
While there is still discussion on the topic its agreed upon that children need to eat at least three times a day.
"I think it’s important to take a step back and consider why young children need to eat more frequently than adults. For example, an adult’s stomach is about the size of a football while a toddler’s is the size of his fist. This is why newborns eat every 1-3 hours around the clock and as their stomachs grow, they can go longer and eventually stop the night feeds."
"By school age, children can move to a “3 meal and one afternoon snack” routine, but timing of breakfast and lunch matter. For example, a child that starts school early (7:30), meaning breakfast is at 7 or earlier, who doesn’t have lunch until 12:30, would need something in between."
How Many Times a Day Should Kids Eat?
Feeding Your Child and Teen: Your Child: University of Michigan Health System