Aussie here as well - I have a pretty high ping to the UK (in the 320-350ms range) but the client connects and runs as well as it does for anyone. I do get stuttering and lag in the alpha, but so do people with ultra fast connections in London. I'd say that NZ would be much the same as Oz. I play a lot of MMOs and my ping usually varies from 80-150ms depending on server location (generally continental US), but I don't have any particular issues with lag.
Try running Ookla Speedtest
http://www.speedtest.net/ to see what your ping and data transfer rates are like. Before running it click on the map, find London, and select Namesco as the server. After you've tested the UK connection try selecting a server in Sydney and see how the trans-Tasman links look. Data transfer is as important as ping, but it would have to be really poor to make the game unplayable.
I'd say that most of the issues we see at the moment will disappear once the bugs are beaten out of the netcode, however it could be that us antipodeans will see a lot of each other if latency is a big factor in instancing.
