I should check the terms and conditions. It might be that if you cease to become UK resident you have to close the accounts and pay off the balances. That seems rather extreme - but it's worth checking before you say anything.
I think I would consolidate the balances into one card for ease of remote management. Cancel the other cards. Then pay off from a UK bank account into which you can T/T funds from Australia as you earn them. Or consider a UK personal loan to pay off the cards and pay this off from a UK bank account by DD (or whatever).
Incidentally, when I was overseas, CapitalOne was quite happy to block the issuance of replacement cards on my account. I think this is a good idea.
I think you will have to at least keep some kind of account running in the UK to pay stuff off. I can't see how you will get credit in Australia to clear the balances before you've lived there for a while.