UK Consumer Law and how it works.

Batteries of any kind are considered consumables; manufacturers will quote a typical cycle life before they begin to decay .

It's typically in the low thousands however there are many caveats to that , including climatic and general charging techniques.

Unless the battery pack has clear failure points notable swelling frankly it's difficult to claim out of warranty free replacement .

Even then the labour costs would be chargeable quite legitimately.

It would also be exceptional difficult to claim under the EU/UK 6 year warranty terms as you WOULD need to prove the battery failure was a result of a pre-existing engineering fault.

Apple iOS devices do include warnings on battery health so afraid many of the legal routes have be well and truly covered .

No one here is a search engine and this is not a consumer law or consumer advocacy Website.

This is a user to user Apple product technical support community.

We are all just volunteer Apple product users here, from all over the world, just like you.

Many people/users visit here.

You need to do your own research on this and not rely on the possibility of others coming to this post with possible answers or solutions to your dilemma

This support area is for product technical support, not about information on consumer law and rights in various countries.

Sorry & Best of Luck to You!

iPad Service and Repair - https://support.apple.com/ipad/repair/service