Qantas is what you need to get this done 125K points gets you the Concorde on BA booked in Z class.
You may want to try coupon conection and see if you can do a swap for Qantas miles. You may also want to check if award seats are still avaliable before you try.I sometimes have read that there are no seats avaliable and then someone says they opened up,you may want to do a search on this.