Dual citizenship - Bulgarian and English

I am a Bulgarian citizen, born in Bulgaria. I have lived in England for 15 years and have been a British citizen for two years. I currently have dual citizenship - Bulgarian and English. In a year I plan to return to Bulgaria. I need information about everything that is ahead of me - do I have to close anything here, can I keep my bank accounts? What happens to the insurance I have paid? What happens to my pension when it comes time? I am interested in any information regarding moving to live and work from one country of which you are a citizen to another country of which you are also a citizen. Can I have a temporary address in the UK? What happens to my NIN number? Thank you

Hi ,
 

HMRC cannot comment on future events as legislation and or plans may change . Thank you .

Could I at least get some information on what is at the moment?

Hi Hashime Kyazim,
Please refer to:
Get your Income Tax right if you're leaving the UK (P85)
Thank you.