I had my tubes clamped 4 years ago and recently got engaged and we have talked about having kids. what is the chances without having a reversal?

Depends : You won't have kids unless you do something. Reversals are rarely perfect & could set you up for a tubal pregnancy. You could have a fertility center harvest some of your eggs, fertilize them with dad's sperm & implant your prepared uterus. This would bypass the blockage. All choices have their expense & work attached but if you do nothing, no kids!

Essentially zero: Tubal ligations fail 1/100-1/200 times, unless yours failed you cannot get pregnant - wihout either a reversal or ivf.