I am probably adding nothing new, but discovered a web page about frozen pensions yesterday.
I don't know whether it is correct or not, but apparently you can claim to have your UK state pension updated during periods of time spent in 'unfrozen' countries - although it reverts to its previous level when you return to Australia. This means that not only can you get it upgraded during periods in the UK but also in any of the other countries on the list - including the Phillipines, USA, anywhere in European union and various other places. Advice was to claim the extra, even if its only for a week or two.
Just thought this might be of use to someone so I'm passing it on.