It’s disturbing to hear the UK is /again/ changing the banknotes (according to BBC WS). Does this in any way shorten any deadline to trade-in the previous notes? Will it be possible to trade in notes that are 2 generations old?

I have a couple thousand GBP banknotes. These are the previous style and no longer legal tender. I would get burnt if I tried to exchange them for my local currency because the exchange service cannot sell them (they must send them to England). I believe I can still travel to the UK and exchange them fairly legal tender at post offices, correct?