How to register and obtain UTR Number

I have contacted HRMC Self Assessment several times, but advisors of HRMC hotline cannot provide advice for solving my case. I don't know how to register and obtain an UTR Number because I am new to UK from Hong Kong. I am retired with interest income only. When I go through SA1 form, there's no box for me to indicate interest income if I am registered as 'not employed'. What can I do for register an account for self assessment and obtain my UTR numbers? Any advise.

Hi,

If you complete the onscreen fill in, print and post form, you can answer yes to the question "Do you have any other other reason for completing a tax return?" and state in the box below the reason you are required to complete a return.

Register for Self Assessment

Thank you.