I received letter in mail from prosecutors stating they will subpoena my hosp records from day of car accident.

I hit car in front of me, I and other driver I hit taken to hosp. I was told by Dr.at hosp that I had a stroke also labs showed blood alcohol above legal limit. In calling attorneys to get quote for hiring them, 2 Attys stated can't give fee due to I have not been charged with anything yet. 2 Attys gave ball park between low to high fee but not definite. Why do I need to wait until I am arrested to get an exact fee? DUI is DUI, no? Other driver injured per my insurance co, he has hired an Atty. I think I need one also for the possibly of what looks like a pending DUI. Will they arrest me or send me a summons to come to court? How do I check on status of possible arrest, as I prefer to turn myself in than be arrested by surprise.