Never received diagnosis letter

Hello 

sorry if I am posting this in the wrong area i am new here. 

I was diagnosed with autism level 1 a few years ago. However the company never sent me or the doctors a letter so there is no formal diagnosis. 

it was with lancashire autism services/btss.org. 

I emailed a lot over the years as the phone line had been cut off. 

The doctors cannot help or advise what to do. the reason I have left it so long is because I have never needed the document however I am starting university in September and they have asked if I have it.

I am not sure if I will need to go through another diagnosis to obtain this. 

Just wondered if anyone else has had this happen or if anyone has any tips 

thanks