Hi everyone, this is how it worked for me
First go to App Store on your device,
drag down to the bottom until you see "Apple ID: ........."
press on it and choose "View Apple ID", will transfer you to the Account page.
My Country/Region was set to Bulgaria, I'm in UK 😁. Basically I was giving UK address and postcode from my Debit Card but the country was different.
Press and change it, then press NEXT and Agree with Terms and Conditions etc.
One last thing, because my country was set to Bulgaria, App Store was Bulgarian too. To change it to UK I did "Turn On Genius for Apps" and then it switched me to UK store.