I know that rental profits are computed using an element of depreciation in Australia but that doesn't apply in the UK. Take a look here for information on computing rental profits for UK tax purposes.
As you are resident in the UK, you have the following options:
Take a look at RDR1 here, in particular section 9.
As a non-UK national, ie non-UK domiciled, you have two basic choices:
1 You can be taxed as any UK national resident in the UK is, ie on their worldwide income with credit being given for foreign tax paid.
2 You can choose to be taxed on your UK income and on non-UK income that you remit to the UK with credit being given for Australian tax paid on Australian rental income against any UK tax liability on the same income.
After you have been resident in the UK for 7 of the previous 9 tax years, you will have to pay the remittance basis charge if you wish to continue to use the remittance basis of assessment. See paragraphs 9.29 to 9.43 of RDR1. The charge increases after you have been resident in the UK for 12 of the previous 14 tax years. After you have been resident in the UK for 15 of the previous 20 tax years, you are for all intents and purposes taxed in the same was as a UK national, ie on worldwide income. See here.
I suggest you appoint an accountant or tax adviser to look at your situation in more depth. It may be that you don't have a UK tax liability.
I hope this helps but let me know if you have any further questions.