Answer
All fares on long haul flights, such as to australia, are extremely much the same - its a question of getting what you pay for.the cheapest flights are like commuter buses and it will take you quite literally some days to get from the uk to australia. the more "upmarket" flights are quicker - take your pick.if you can take the risk of waiting for a cancellation/spare seat, then hang on in there for last minute resellers such as lastminute.com, otherwise check out your local travel agent and just plain go for it.
