Basically it is a powder that has many great uses, from
baking, cleaning, getting rid of odours and for
home remedies.
You can get it from general stores and supermarkets. In the supermarket you will find it in the baking section. Dr. Oetker Bicarbonate of Soda. You may find some unbranded packets. Dr. Oetker Bicarb is not that expensive. Do not get baking powder or raising powder - these are a mix of bicarb with Cream of Tarta (a powder to stablize egg whites).