Hey I can relate exactly to that fear of failure that you describe.
My post that I wrote after trying to get positive after my last relapse titled "The thing thats bugging me" was written about the axact same feeling.
That niggling anxiety/worry in the back of your mind telling you that inevitably you will drink again was really doing my head in. I shared about this at my AA meeting on Monday on broke down in tears crying whils't sharing about it and how it is stopping me from being able to progress in my life.
I am not worrying about things relating to drinking in the future but making sure my thinking remains in the 'One day at a time' mantra. I am building up the mental strenght on a daily basis to make sure that I do not pick up that first drink. It is a kind of irrational fear in some ways as at the end of the day it is me, and only me, that will have to physically go out and buy booze and then gulp it down my neck, no-one is gonna force it down me. it is just that it almost becomes something which becomes second nature, in certain situations at at certain times, and thus feels like it is not possible to not have it, but it is indeed possible.
I just try to think back to when I was 14 and I had great fun/enjoyment without any need for alcohol and it never crossed my mind.