Hi Robin, thanks for your answer. Unfortunately, it's still not clear for me, I hope you can help me understand better the situation.
Indeed I'll be back in Australia soon and still are, and will be, Australian resident for tax purposes. However, I'll be also trading in the UK within these 6 months, thus I'll have to register and lodge an assessment here. I'm aware of that.
My question is about how to pay taxes for a work realised in a country and paid in another. I haven't been using a particular accounting method because I just started freelancing but had I been using a cash accounting method before wouldn't it make more sense to register the income and pay taxes when and where I receive that cash, otherwise (using the accrual method) I'll be acknowledging a revenue and liable for taxes for something I haven't been paid (I know I could get back the taxes in the future if I'm not paid but I rather not do that).
Also, remember I can be paid (and would rather be paid) in a UK account and haven't send any invoice yet, so that I would be able to send a UK invoice once I register.
I wonder which are the implications of sending a UK invoice to my client and receiving the payment in a UK bank account when I have done the work in Australia, incurred in expenses there, and of course when I wasn't registered in the UK taxation office yet.
I hope I was clear this time and you could help me further.