If you need to send excess baggage, you should consider doing it with a freight forwarding company, as airline excess baggage costs can be quite considerable.
For example one of the major airlines charges AUD$175 for 5kg of Pre-Purchased Additional Baggage from Australia to the United Kingdom.
You should refer to the airline website that you will be travelling with to find out what their baggage limits are well before you travel so you don't get hit with an expensive charge at the airport on your departure.
Listed below are freight forwarding companies that can organise to send your excess baggage back home to avoid the expensive excess baggage costs of airlines.
Pack Send - Phone 1300 668 000
Seven Seas Worldwide - Phone 1300 216 698
World Baggage - Phone 1300 714 422
Jetta Excess Baggage - Phone 1300 300 688
Ezi Baggage Services - Phone 1300 394 224
Baggage Masters - Phone (08) 8352 1355
Luggage Line - Phone 1300 665 110
Qantas Courier - Phone (02) 8337 8900