Drinking means different things to different people. Because of my a fib I was advised not to drink. When I brought up the subject with my cardiologist and told him my "drinking" was no more than one beer or a glass of wine a day, he said not to worry. If "drinking" means more than that, I would certainly be cautions due to a number potential health problems, heart being one of them. Certainly an honest discussion with your doctor could help clarify the issue for you.
It takes awhile before you can tell if the ablation was truly successful. How long has it been? If it's been 6 months with no a-fib then that's pretty good. You could ask your cardio, see if it's OK to try a small drink. I've had 3 ablations for tachy problems and I still can't tolerate alcohol. At most I can drink 6oz of a mild beer. Oh well, at least it isn't something critical like water or chocolate (just kidding).