I need to post two standard letters to Australia. Looking on the Royal Mail website, it seems it will cost £2.25 each, which is fine.
Am I allowed to use my first class domestic stamps to make up the £2.25 value (approx 4 stamps each), write air mail on the front and then put in the regular post box? Or do I have to attend a shop, stand in line for three hours and buy a special stamps?
They don't need customs declarations.
Thanks for any advice :)