G'day again Mick - at least you've got the right name to be on the Aussie Forum.
Most of us in the land of Oz ride all year round - the only limiting factor for most of us is heat - let me assure you riding in 38c+ is just as unpleasent as riding in the cold.
I'm a firm believer in the adage "If it's too hot to wear the right gear, then it's too hot to be on the bike".
Consequently from around mid December to late January I usually limit my riding to early morning or late evening. The only problem with that is the Wildlife. Hitting a Kangaroo, Wombat, Echidna etc at 100km/h is not fun - not that it's happened to me, but I know of people who have, and I've seen some pretty horific pictures. But, if you ride with this in mind you can ride fairly safely.
By the way, you should feel at home on the Aussie/Kiwi forum, there's a few of us that come from pommy land.
Myself, I was born near Bradford - Mum and Dad moved to Oz in '70 (I wasn't even 5 then) so I don't really remember much. All my Aunts/Uncles/Cousins live in pommy land so I get to hear about how lucky we are downunder.