@joe8352: Sorry to hear that you've damaged your S21 screen. If you did want to look into having the device repaired then please reach out to our Help Desk on 0333 000 0333, or via Facebook or Twitter, and an advisor will be able to make the necessary arrangements for you. I'd always recommend repairs such as this where possible, as the cracked screen may lead to further issues with the phone.
Check any Home Contents Insurance for cover and some Bank Accounts provide cover as a perk of the account.
Check excess fee's and be aware your payments may go up when you renew.
If the damage isn't too bad then perhaps purchase a Whitestone Dome Glass Screen Protector as they can help to cover the damage too.
This is my preference of Screen Protector.
They are not cheap but are regarded as one of the best available.
Current Phone > Samsung Z Fold³ 5G.