Thanks guys.
I have been trying to check the fare on JL website but it gives me a really high fare when I try to make an open jaw booking (ex SYD-NRT-CDG // BCN-LHR-NRT-stopover -SYD). I checked the fare for same route on NH website and It only costs AUD 2150 for May 2017. I think I will fly on NH this time. Thanks all for your help!!