In reply to JRZ:
Re: Melbourne and Victoria in general - do a search around 'Grampians access issues' - there's a lot of tension between climbers and Parks Victoria (the organisation that manages the national parks) around access to climbing venues at the moment.
Re: timing - problem with avoiding the winter months in the UK is you get the really hot Australian summer months. Aside from having to drop grades due to the sweat factor, there's also the risk of Bushfires, or crags being closed to recover from bushfires. (This happened to me in 2014 when I lived in Australia - was hoping to climb at the Grampians over Easter, but most of the crags were closed due to fires a few months earlier)
Whilst the above sounds quite negative, there is some great climbing in Australia - just not quite as simple (or cheap) as a climbing trip to Spain in winter.