Hi guys im new to this airmiles thing etc,lets say im moving to oz next year should have my flights sorted out for the london to perth trip soon,but im looking to use my avios points/miles for the scotland to london part,i wanted to ask what does this mean:


9,450 Avios or
8,505 Avios + £10.50 or +£35 reward flight saver
7,560 Avios + £21 or
6,615 Avios + £31.50 or
5,670 Avios + £42 or
4,725 Avios + £52.50

there will be me and my wife and our baby who at the time will probably be 8 months old,i take the above points to the left is what is needed or if looking to use less points i can pay the amount on the right?so what is this reward flight saver to the right??
Im sure this is on the left the points needed for us three and i take no other fees payment are required?
It says this:

Reward Flight Saver

We pay the airline taxes, fees and charges for these flights - you just pay the Avios fare + £15.00 one way

what does this mean?

I have 12,500 avios points to use,if i have some left over then great im sure someone said i can use them in oz sometime so any left can be used then if i need to use most of them and may no money or little of it then im sure i have enough points,any advise would be great