is a wonderful thing!
Just in case this helps anyone who hasn't yet left the UK, thought I'd write a quick post on it...
Before we left the UK, we managed to get a PO Box in Christchurch reserved for us (there are some previous threads on this if people are wondering how).
Then while still in the UK, we set up for all our UK mail to be forwarded to the PO Box in Christchurch. This has actually turned out to be amazing value, as not only do we get all our UK mail pretty promptly, but we also worked out that rather than ordering OH's top gear magazine subscription as an international sub (£80 versus £33 for UK), we just renewed it to our UK address and now it gets forwarded automatically along with everything else - first one arrived today.
We've also discovered that anything that we order by amazon, for delivery to our UK address, that is sent out via Royal Mail, is also forwarded out here - all at no extra cost to us!
All of a sudden the cost of Royal Mail international mail forwarding seems a bit of a bargain!