Just picked some of this bath soak up in our local store (Alfreton) and its scanning at 1p.
If its anything like the other Tesco 1p deals, the product might not be available in all stores.
Its the yellow bottle shown in the photo.
Details off the bottle -
Tesco Radiant Glow, Herbal Bath Soak, with extracts of Passion Flower & Mimosa. 750ml
Barcode - 5 051399 538839
Our Tesco only has the yellow bottles so don't know if other colours are reduced.