The DVLA will not accept any other than a cert issued by a DVSA authorised
inspection centre , and they are only in UK .

If you are on a aus registered bike in UK , then if it has been in UK more than 6 months it should possibly be registered in UK , you are risking having it siezed by police . There is guidance on the GOVUK website ( https://www.gov.uk/importing-vehicle...porary-imports) They are increasing action on foreign registered vehicles , due mostly to abuses of the system in EU by EU migrants to UK , who are using insurance issued in their home country , which is technically invalid, and results in car being seized, untill they comply .

I dont see why you cant insure your bike in UK there is no requirement to have MOT , other than the condition that you maintain vehicle in a road worthy condition , which could be checked in event of a claim .
You will find it almost impossible to get a insurance that is valid as part of EU laws require that insurance is issued by the country where the vehicle is registered and covers liability thruout the EU .
There has also been uncovered some dodgy MOT centres who were issuing MOT to RVs without them returning to UK from such as Spain .
So looks like your only answer will be return it to UK on route to Europe,there is a consultation underway for unifying acceptance of MOT issued in any EU country but at the moment this is only looking at heavy goods vehicles, so not likely to be able to address your problem in future .
HTSH

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Current : 2007 Mowag Bucher Duro 6x6 Motorhome , 2006 Sedici 4x4, 2007 Range Rover supercharged