Hashime Kyazim

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

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