I thought I would share this informative little tip I found in the Etsy forums a few months back.
I am yet to try this myself (I keep forgetting) but apparently when clicking on the link below and filling out the
appropriate shipping details, the site will give you an extra 4 digits to add to the post code.
Zip Code Lookup
Photo Credit - Ihearttely
The extra 4 digits is apparently supposed to half your received orders shipping time, leaving only happy customers.