Found these descriptions
Zucchero Deep red plum tomato (from B&Q/Suttons)
Classic Italian plum tomato from the San Marzano region. Fruits are deep red inside and out. Excellent for slicing as it has few seeds and a meaty texture. Also ideal for sauces and pasta dishes. Harvest August-October.
Zucchero F1
An indeterminate variety with up to 14 fruits per truss, even fruits of 225-30grams, large cherries/small cocktail type
I think from the name it should be sweet although the two descriptions are differing?!