Phone sim question...visiting Australia

[StillMedusa]

Dh, DS2 and me are off to Oz in a fortnight to stay with DS1 for three weeks.
We can use out Giffgaff sims BUT only by paying for a ton of credit.
Would it be cheaper to get PAYG sims there, does anyone know?

If you buy a PAYG three SIM card in the uk, top it up in the UK and pay for their unlimited package and you can use it in Oz as would at home for no extra charges as it is one of their "At home" countries.