Hi,
When you prepare your UK Self Assessment return you have to ignore what you put on your Australian tax return and start with your gross Australian property income and deduct only what is allowable in the UK. The guidance on replacing domestic items is here:
Allowable expenses
You can also see information guidance on the paper SA106 notes:
Self Assessment: Foreign (SA106)
No, as interest is deductible on your Australian tax return it does not mean that it is allowed in the UK. You can however add your residential property finance costs in box 24.1. This will give you a deduction 20% of the lower of either the finance costs, property profit after deducting losses brought forward or your adjusted total income. We take the tax that you have paid in Australia into account in box C and box 28 page F4.
Thank you