iPad mini - same in Australia as UK?
According the LTE page at Apple.com the model in UK and Australia should be compatible:

Model number:


  iPad mit Retina Display (4. Generation) Modell A1460
  
  iPad mini Modell A1455


LTE Band Support:


  1 (2100 MHz)
  3 (1800 MHz)
  5 (850 MHz)
  13 (700c MHz)
  25 (1900 MHz) 


For both UK and Australia. You should be fine buying the iPad down under :)