I'm porting my 021 number back from 2degrees to Vodafone, because 2deg don't have a reliable text messaging infrastructure. If I do it online how do I get hold of a SIM card? I wouldn't like to port my number online, have it move straight away, but then not be able to use my phone until a SIM got sent to me in the mail.

Is it easier to call into a Vodafone store to do the porting? If I do this what documentation do I need to bring in?

The Vodafone website doesn't seem to have anything about porting a number to Vodafone On Account, at least nothing I can find. I found the page for prepaid, but that's not helpful.