It is notoriously difficult to prove that a crack is the result of a manufacturing or material defect. As such, screen damage is often excluded from warranty claims.
Apple offer a limited one-year warranty - against which you might attempt to make a claim. If making a warranty claim, you should first attempt to make a claim with the retailer from which the iPad was purchased in the UK - as it is the retailer with whom your purchase contract (and therefore your warranty) principally exists. If unsuccessful, you then have the potential backup of making a claim against the manufacturer’s limited warranty.
If you had the foresight of opting to purchase Apple’s AppleCare+ plan, this being an insurance product, you will have the security of being able to make claim with Apple regardless of fault. In such circumstances, a small excess/deductible charge is made - and you will receive a replacement (usually a reconditioned iPad of the same model and specification) iPad.
For practical purposes, in lieu of repairing and returning your own iPad, Apple usually exchange the iPad for a renewed/refurbished iPad of the same model and specification. The cost of the exchange is the same as would otherwise be charged for repair. Unless you have benefit of an active AppleCare plan, an out-of-warranty repair while expensive will be somewhat less than the cost of a replacement iPad.
As for out-of-warranty repair costs, Apple offers a fixed-price price repair. You can verify eligibility and cost for your region/country here:
iPad Repair & Service - Apple Support
If you have an active AppleCare+ plan, the cost of repair is reduced to a small excess/deductible fee.