You will need to ask the sender for the name of the suburb to be picked up, the postcode and an exact size and weight of the consignment.
Then simply google "UK to Australia couriers". Just go to their website and ask for a quote. In most cases the website will give you an immediate price. Prices will vary between companies significantly. Some companies will be cheaper with smaller shipments, some cheaper with larger shipments. You may find it is cheaper to arrange payment from the UK end rather than from this end. It will also depend on how fast you want the goods to arrive. A good starting point is ParcelBroker - UK.