Ok jomtien/chonburi immigration you will require current tm30 for extension just completed mine there that is a sticking point for them basically mandatory at that office
I don't believe there is any long term visa available to you as you are a German passport holder residing in Australia for travel and work purposes not even sure with your nationality status allows you to apply within Australia
60 day tourist visa for Thailand even if you can sometimes the thai authorities take a dim view with tourist attempting to stay long term on tourist visas and you maybe questioned about your number of entries don't be surprised if you are denied entry at some point entry to Thailand is never a guarantee it's all dependent on the IO infront of you at time of entry Chokh di
Why would someone stay 8 days over the 30 day stay you either get 60day tourist visa in UK prior to departure or 30 day extension 1900baht at thai immigration either way why wouldn't one stay that extra 30 days
Mmmm iam confuse who would've thought there was thai embassies in Bangkok you want to travel and extend your stay visit all these place including visit to the islands but you have limited funds must be a trick question