Taxed at BR instead of PA by Former Job

Hi there! I worked in the UK over the summer and made well-below the personal allowance, but unfortunately my income was taxed at BR. I wasn't able to change this in my tax app as I was unable to get a national insurance number, despite going to a job centre to get one. I have since left the job and have returned to Ireland, and I will not be working in the UK for the remainder of the tax year. My former employer sent me a P45 as I left, and it says that my tax code upon leaving is still the BR. Is there any way that I can change my tax rate and claim my tax back, as I only made £4,000 and will not be returning to the UK this year?

Hi,
To claim any tax due back after leaving the UK you need to complete the form P85 which you can find here:
Tax if you leave the UK to live abroad
Thank you.