Yes, customers in many parts of the world need place orders this week to be sure of Christmas delivery, even those in the UK only have a couple of weeks. International Airmail last posting dates are as follows:
Mon 5th December: South & Central America, Caribbean, Africa, Middle East, Asia, Far East (including Japan), Australia and New Zealand
Fri 9th December: Eastern Europe, USA and Canada
Mon 12th December: Western Europe
Courier delivery will still be possible after this. I normally ship heavier or higher value orders by courier as a matter of course. However, I can ship other urgent orders by courier if you pay the difference.