This deal from Coles Credit Cards doesn’t seem to bad.

-It appears that for the 15 months you only have to make the minimum repayment to be interest free.
-Good for some Arbitrage.
-Remember not to get into too much debt and pay off total at end of period.

Terms and conditions from website.

⁰ Credit criteria, fees and charges, terms and conditions apply. New customers only who apply by 31 December 2018. 0% p.a. will apply to Retail Purchases (excludes Cash Advances) for 15 months from the date your account is approved. Minimum monthly repayments required. At the end of the promotional period, any outstanding Retail Purchase Balance and any new Retail Purchases will attract the variable Annual Percentage Rate for Retail Purchases, currently 19.99% p.a. for a Coles No Annual Fee Mastercard and Coles Rewards Mastercard and 12.99% p.a. for Coles Low Rate Mastercard. Interest rates are variable and subject to change. This offer cannot be used in conjunction with any other offer and is not available when closing/transferring from another Coles Credit Card.