Thanks Bob. We had the RNATT Declaration done about a year ago and yes we did it ourselves with our vet. However, this is due to not being certain when we were going to move to Aus which was determined by our property sale in the UK. But since the RNATT declaration is valid for 2 years, it meant that we could organise the rest for the cats relatively quickly once we sold. I'll report back on what happens with the import permits.
You are right though - I definately will be using a "pet mover" company for the actual transport part of the animals. Much less stress!