That's great news! Just be honest, I think? You have to start the process.
Have you spoken to your GP about the specific problem you are faced with now before, if you don't mind me asking? Practically, the doctor won't be able to formulate a sensible plan unless they know everything.
For me it was daunting to have to open up to my doctor about the truth, but that is surely what you have to do? There really is no point in trying to downplay your problems (your addiction would love that, of course!) For me. once it was done, the feelings of relief were palpable.
From my own experience, lying to the doctor is a mug's game. I did it for years to protect my "right to drink." [Not suggesting you would be so stupid!]