Buy a base ipad during Prime Week or Back-to-school time?

I'm looking to buy a base ipad (128gb), because well that's the cheapest one. I already have a tablet but I've wanted an ipad for a while and have been making arrangments for my transition.

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My question is, when will I find it cheapest: prime week or during apple's back to school offers. Prime has already a price cut in the base model so I think it will get cheaper during prime week. And I hear base model ipads typically don't get a sale during back to school.

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Also, i am in the uk. Hope someone can help me!