Left UK and did not realise I had to inform HMRC. What should I do now?

Hello, I left the UK over 10 years ago and have lived abroad in different countries since. I am currently a permanent resident in Germany and have been here for 7 years. When I left the UK I did not inform HMRC, actually I did not realise I needed to do that until I read about it this week. What should I do to rectify this situation, is there a penalty? I hope to return to the UK in the next few years to be closer to family. Thanks in advance for your help.

Hi, Just complete P85 form, giving the date that you left the UK. You can find the form in the link below:
Get your Income Tax right if you're leaving the UK (P85)
Thank you.