Sarahgoring

I am a UK national living overseas so I'm not paying tax in the UK. As a non resident I can't find a UK savings account that I'm eligible for so I am saving money in an overseas account. If I move back to the UK I would want to transfer funds back so can I check, would I pay tax on all interest accumulated in that account over multiple years at the time of transfer? So for example if over 5 years I have earned £20,000 in interest, would that full amount be taxable immediately on transfer? Thanks