On arrival, United Kingdom applies Transfer of Residence (ToR1) relief under UK customs framework (jurisdiction-specific). Import VAT in United Kingdom is 20%, and relief is what keeps your household goods out of that charge. Shipments normally arrive through Southampton or Felixstowe.
This page covers what actually changes on the Australia → United Kingdom route: what you will pay, how long the shipment is at sea, the paperwork United Kingdom customs expects from a departure in Australia, and what to do about pets, a vehicle and somewhere to live when you land.
Departures from Australia normally load at Sydney, Melbourne, Brisbane. Exports are declared by the forwarder. Long-haul sailings out of Australia are less frequent than northern-hemisphere trades, so departure windows matter more than transit speed. In-home and video surveys are both widely offered.