Hi .....
I would recommend Malaysia Airlines for a number of reasons:
1. Leg room - they have the most legroom compared to other airlines. (economy class)
2. Price - one of the cheapest especially for students - try rex air (travel agents in London, my last flight to Melbourne cost me only £530 - including stopovers in KUL and SDY)
3. Modern fleet - for the journey from LHR - any Australian city, they only use B744 and B772 (if your lucky get onto the newest B774 ...weeks old)
4. Service - won best cabin crew 2002, wonderful service
I have tried BA, Singapore and Qantas.....but now i'm hooked on Malaysian.
Hope this is helpful
p.s. on most of the KUL-Australia sectors the flight is not too full, you can have 3 or even 4 seats!!! Pick the right flight!