Yes all newer stamps have bar codes Jenna. Only bar coded stamps will be valid after 31st of January next year unless they're commentorative stamps. Your recipient will be charged unless it's going overseas then it won't be sent. I know you do postcrossing Jenna so if you're like me and have a stack of stamps in different dominations you're better off using them now rather than waiting until they expire.
Here is a link that explains the changes
https://www.gloucestershirelive.co.u...become-6656097
It's also validated in the British Isles part of the postcrossing forum.
Emma you cant swap non bar coded stamps for the new ones at the post office. You can pick up the form once it's available there but you have to send the stamps off in order to receive the new bar coded ones.