by blondie » 07 Jul 2015 14:56
Hi - as far as I know, you can still pay at the airport for the time being, although it will cost you £20. As for the passport issue itself, the official government website does state that you need six months on your passport and doesn't seem to make any distinction between applying online or at the airport. In fact, since the beginning of this year, you also need 60 days' validity on your passport from the expiry of your visa, making it in effect eight months rather than six.
Personally, I would try to renew your passport if you can rather than take the risk