The only really convenient times (i know because i speak to family back home in the UK) between there and Australia is currently 11am UK – 8pm East coast Australia on Saturday/Sunday for both timezones or a variation slightly earlier/later.
UK evening due to the approx 3hr negative time gap means that the most reasonable time would be 9am Eastern Australia and Midnight UK. Cant see many making an earlier than that time slot even on a weekend. West coast Aus would be even worse for an evening GMT meet up.
Can’t see us making many meetings until the clocks change again in October when 9pm UK becomes 8am in Aus.