Immigrationboards.com

Hello, I am sorry in advance if I am posting in the wrong section.
So recently I found out I needed to get British Citizenship because I want to join the Armed Forces in the UK.
I am currently 17 and around 5 months and I have been in the UK for almost 10 years. I am originally from Lithuania.
I just wanted to know how I could prove how long I have lived here for. And I was also wondering whether I am eligible to register as a British citizen.

what was you doing during last 10 years? did u attend schools?
how about your parents, did they work? are they thinking about naturalization?
if not you will have to wait to you are 18 and than get naturalized yourself.
if I was u I would sort out my permanent residency permit using your parents workers status and yours schools paperwork and than get naturalization done.
bear in mind that you gonna loose Lithuanian nationality as Lithuania does`t allow dual nationality.