Not strictly low carb, but much lower carb than standard Ice cream - excellent for a treat at 10 grams of carb per hundred grams:

Minghella Dolce Vita real vanilla Ice Cream for Slimmers and Diabetics.

100 grams provides:

Energy 109kcal
Protein 3g
Carbohydrate 10.6
of which fructose 6.2g
Fat 5g
Polydextrose 7g
Sodium nil
Calcium 107mgs

It tastes really good and is less 'sweet' than normal Ice Cream - which I personally like. 100 grams of this is a decent amount.

I found it in Tesco