You’ve edited this to just say ‘no’ on your op btw.
But to answer your question, in my opinion if you demonise sugar kids go to wild lengths to get it. All kids have a sweet tooth, it’s a hangover from how sweet breastmilk is!
For me it was very important to never ever have good food and bad food. All food is food and nothing in our house is off limits. What I do teach Dd is that some foods have more things in them that help us grow and get stronger and feed our cells etc. so using science rather than emotive languages.
I have a ‘candy’ drawer that Dd can help herself to pretty much whenever she wants. But because it’s never been off limits and she knows that yes even if it’s 5 minutes before dinner she can have a gummy bear, she’s never gone wild for it.
I also have fruit/veg/nuts etc freely available and more often than not she’ll want pecans over chocolate.
If you make something taboo kids want it. So no I don’t think having sweets at school is a bad thing.