NEW MONEY IN BRITAIN
If you have money from past visits to Britain, please know that this week a new ten pound note goes into circulation and the old notes will no longer be legal tender. The five pound note has already been in circulation. The one pound coin has also been re-designed and now has eight sides, the old round coin will no longer be legal tender as of this week. Some stores will try to give you old money in change but you can refuse to accept it. I am thinking the twenty pound note will be the next note to be changed, so be sure to spend any of those old notes before you leave Britain on Any upcoming tours.
"When do Bank of England notes stop being legal tender?
Bank of England notes stop being legal tender when we announce that they are withdrawn.
Before this happens, a newly designed banknote is produced and enters circulation. Bank of England notes keep their face value for all time. If your local bank, building society or Post Office is not willing to accept them, then you can exchange them for new notes at the Bank of England.
For the most recent note withdrawals, we publicised the withdrawal date three months in advance. For the most recent paper £5 note, the period was longer: it stopped being legal on 5 May 2017."
The Bank of England is in London, there is only one. You must have a British Bank account where the exchanged money can be deposited, that is how they give it you. Or if you want to put it into your US Bank account, you have to provide theSWIFT number etc but the banks can charge you for this, sometimes for both transactions and it is not cheap. I think if you take notes to the post office, they will also give it by way of a bank account.