The last order date to get delivery by Christmas Eve is Friday 17 December.
This time of the year the postal service is obviously very busy and things slow right down. Based on previous experience even when sending with first class post (which is included on all orders) it can take 5-7 days for deliveries to arrive. With that in mind the last day that you can order to receive by Christmas Eve is Friday 17 December. Any orders placed after this day can't be guaranteed to make it.