How to complete self assessment from a few years back without access to NI and from abroad?

I am a Belgian national who lived and worked in the UK from 2011 to 2018. In 2018, we moved back to Belgium. A few months back, we started getting letters from HMRC with penalties because I hadn't completed a self-assessment form from 2019 onwards. I few weeks back I had an online chat with an agent who told me i had to fill in these self assessments so the penalties would stop increasing, afterwards I needed to appeal the penalties. I am trying to complete the first step but I can't seem to do so... I can't login to the gov portal since I no longer have access to my NI number since we moved out in 2018. I also tried different communication channels but non seem to work. I also can't seem to talk to an agent anymore... The online bot says he cannot redirect me since advisors aren't available. There is no email and I tried calling +44 161 931 9070 which is listed on the self assessment page for help outside the UK but if I call them, they say it's only to order leaflets and forms but they can't help with self assessment queries. I can't seem to find any relevant information that helps me.

Hi,

Agent availability does depend on when you contact us by webchat, availability can vary depending on demand, but advisors are usually available between 8am and 6pm, UK time.

We are sorry you did not receive the advice you needed when you called our Self Assessment team, however if you contact them again we should be able to give you more advice.

Self Assessment: general enquiries

If you are unable to file your returns online, you can request to have paper returns sent to you to complete and send back here:

Self Assessment: forms ordering

Thank you.

 

Maybe another question... Since I haven't lived or worked in the UK in those years, I don't need to fill a self assessment, correct? So do I really need to order the SA forms? Would it be sufficient to appeal this and will this sort this out? What exactly is the correct procedure for me to follow to sort this out?

Hi,
If the tax returns are for the tax years before 2022/23 then normally it would be too late to withdraw the tax returns.
The tax returns would need to be filed and then an appeal made against the penalties.
You can file the tax return online from the 2020/21 tax year, before that tax year it would need to be the paper tax return.
You can download the paper return Self Assessment tax return forms.
To review the tax years 2022/23 onwards you can contact us by phone/webchat/letter to review Self Assessment: general enquiries
Thank you.