"Geographic" cures don't work any better for us than they do for alcoholics.
If I were you, I would ruthlessly examine my motives for wanting to make the move (do you really think it would be a better life there? How is the job market for you? Do you still have close friends there?). Moving a long distance just to get a clean break can wind up making you feel stranded and bring on additional problems.
If, however, you are sure it would really mean a better life for you and the kids (and you have some evidence to back that up in the event he tries to legally block the move), then it is worthy of consideration. Bear in mind that if you are the one instigating the move, you may have the financial burden of making sure the kids are able to spend time with dad.
I had to move across the country from my kids and my sober ex several years ago, but we have always cooperated on the parenting and shared the costs invoved in my going to see them a couple times a year. It can work, though it would be tougher with one parent who is an active alcoholic (EVERYTHING is tougher with one parent who is an active alcoholic).