What exactly do I declare as a non-UK tax resident on my property in the UK

Hi, I am a non-UK tax resident but I am a UK citizen. I own a property in the UK and want to declare the income I have received on it. I know how much the flat is rented out at, but I also know I am allowed to deduct allowable expenses as well as having a UK personal allowance. Keeping this in mind, how do I declare the income as a non UK tax resident? (I am finishing my sign up for self-assessment but there have been some issues that I am dealing with someone on the phone with). What form would I need to fill in and would it be online or by post? Am I right that I would declare the income I received, then that my personal allowance would then come into play, and then I would declare my allowable expenses (such as service charges, letting agent fees,...) Thank you for your help!

Hi kat. Following your question hope you get a reply

Hi katquestion,
Please refer to the link already provided.
Thank you.