There are degrees of heartburn.
For "normal" heartburn, milk and gaviscon will help enough.
However, for serious long term heartburn, zantec helps, as it actually reduces the amount of acid your stomach makes, whereas Gaviscon just sits on top of it like a foam.
I had HB so badly I ended up at a gastroenterologist who gave me a prescription for something even stronger than zantec.
He also said to avoid fresh bread, as the yeast in it activates stomach acid. He said milk helps for a bit, but then the stomach reacts by making more acid, so a short term solution.
Hideous HB is one of the reasons I am worried about getting pregnant again. I spent a month not being able to lie down due to reflux, and trying to sleep sitting up.
It is agony, isn`t it?! I think the oat slime would also help, if you can get it down. I found regular carb based small meals were the way to go.