I have an allergy to yeast which rules our all beers and wine. However I have heard that are certain brands of champagne / wine that has no yeast or yeast extracts. Can anyone help me on this one

Sorry, you have been misinformed because champagne or good wine cannogt be made without a quantity of sugar solution and yeast called the 'liqueur de tirage' sealed in the bottle.

I guess some non alcoholic brands are not made this way.

It is not possible to eliminate the yeast or yeast extract and still manufacture a wine or champagne that contains alcohol. Alcohol is the byproduct of sugar and yeast. If a beverage contains alcohol, in any amount, it also contains yeast. Even some so called non-alcohol beers contain a small amount of alcohol, thus containing yeast.

Also, drinking wine or liquor seems to aggravate a yeast allergy far more quickly and at a more intense level than beer. I’m not certain why that is, but it is best to avoid.