Yes it is, I know of shops which which will not take cash, card only, there is online banking, try finding a Bank which will allow you to open an Account in a Branch. There are sizeable towns without a single Bank the public may visit, and the Manager, nowadays a Financial Product Salesman.
From the Bank of England website there are £82 bn of banknotes in circulation.
A reminder, if you have notes hoarded away, check for the presence of the old non-polymer notes, they are withdrawn at the end of September 2022 and cease to be legal tender, and should be surrendered to a Bank for exchange.