Except that was when I was trying as a guest, when I logged in under Edge, same thing! My Postcode begins with PO, but as above, I have ordered countless things on my Airfix account.
Still an issue, I have emailed them, but judging by last time when I had a duplicate sprue in a model I ordered (so I was missing one), it took over 4 weeks from response to actually getting the missing sprue, by which point I'd gone off it.
Is anyone else having issues with ordering from the Airfix web site? When I hit the proceed to payment button I get... "Unable to post to a PO Box" Despite using the same address I always use.