The weather here is NOT "perfect". It has its vagaries as much as the UK, only a bit more extreme. The spring and autumn are generally lovely, fair dos, but summer can be unbearably hot and muggy, and if you live in a water restriction area (so glad we don't but we know people who do), you can just watch your garden die waiting for the rain. Fine if you have no interest in gardening or growing your own veg. Some days we just stay indoors with all the curtains closed to keep the sun out and the air con on all day. Doing anything remotely strenuous (like hoovering) causes you to break out in a muck sweat.
It's winter here now. Older houses are not set up for winter, unless in areas like the Blue Mountains or other mountainous regions. Ours sure as hell isn't - it's freezing inside. I've not been this cold in a house since being in my grandparents un-centrally-heated house in Sheffield when I was a child.
Central heating is very rare; reverse-cycle air conditioners do pump out heat as well (we don't have one) but the cost of the electricity is huge.
It rains, it's cold and miserable, the wind is really something sometimes (especially August). This is NSW.
It does stay warm up in the north; I have a friend in Cairns and it never gets below 20degC up there. She finds it tedious and much preferred NZ (where she was before) because it had proper seasons.
The loss of slow sunsets and long evenings does get to me sometimes - as echt said, it is pretty much like the light being switched off. We do get pretty sunsets sometimes but they don't last long! And it never stays dark later than 8:30pm.
re. the food shopping. I was back in the UK in May and the first thing I did was go to Tesco for a big food shop - my trolley load looked like it would be about $200 (£125) so I was really 
and happy that it was only £87. It cannot be compared, unless you do all your shopping in M&S - food is more expensive over here. However, if you're not bothered about brands you recognise, Aldi is here and is much cheaper than Coles or Woolworths.
I know we are currently suffering from the extreme weather that has hit Queensland in the last few months but bananas here cost ~$14/kg (that's about £8.50) - in the UK in May, they were 69p/kg in Tesco. That's an extreme example but fruit and veg varies week to week in cost, depending on availability, FAAAAARRR more than it does in the UK. Grapes for e.g. can go from $2/kg to about $14/kg.
Another point to make, although it's changing a bit now with the exchange rate - plane tickets FROM Australia to the UK are generally more expensive than those from the UK to Australia. So consider buying returns from the UK.