You don't specify which UK airport is your starting point, or if you will link from the continent, or only wish to consider going direct from the UK.
Starting point = LHR = Heathrow, UK
End point = SYD = Sydney, Australia
Return flight, over a two week(ish) period. Want to fly direct from UK to Oz (don't mind where the stop is). Am flexible on dates.
Sorry if that wasn't clearer in my OP.