There is no deadline to exchange old banknotes with the Bank of England. But it is usually easier and quicker to exchange notes at your own bank or at the Post Office.
9billion in old UK banknotes not cashed in - how to exchange old notes for new ones - Mirror Online
Fact Check: Exchanging Old Banknotes Is NOT Mandatory
There's NO panic to spend your old £20 and £50 banknotes
Fact-Check: Is it true that the UK government will phase out £50 and £20 notes by September 2022? - PRNigeria News
Nigerians face losing life savings as they struggle to swap banknotes
How and where to safely exchange old dollars?
People race to exchange paper banknotes before deadline
How to exchange old 20 pound and 50 pound notes [2023] - Executive Traveller
In what circumstances is £9 in change more valuable than a £10 note? - Quora