Yeah… most policies will automatically extend if you are delayed returning due to insured events, or in this case, a delay retiring due to circumstances beyond your control. But in this case it’s likely to mean medical cover only, and loss of luggage, etc. It’s prolly not going to cover additional hotel expenses or flights home, etc
As mentioned in another thread, anyone currently holding tickets to return to Australia from the UK or Europe will be covered for re-routing by UK/EU261. That’s a legal requirement, and the rerouting can be on another carrier. That only kicks in once the flight is cancelled. No financial compensation for delays, but you also get duty of care, which includes accommodation and meals.
For those regions it’s picks up a big chunk of any potential insurance claims.