In latest version downloaded yesterday to replace previous one, I also downloaded the postcodes zip file, extracting it to the same folder as the sky demon program files.

There is a brief section covering transfering things to the iPad including the postcode database in the documentation, below:

http://www.skydemon.aero/plan/documentation/ipaddata.htm

However please be aware that in the 2.4.4 version of SkyDemon for iPad (2.4.5 is still not quite out) you may encounter a bug where you cannot select the search results after a postcode search.