I think that ALL of the main supermarkets do VLF versions of these - you need VLF of either for it to be free. (I know someone will correct me if I'm wrong!).
In Sainsburys, which we like best, go for the Be Good To Yourself brand, in Tesco it's Lighter Choices - but it needs to be labelled 'virtually fat free' or 'less than 1% fat' to qualify as free.
No doubt there are some exceptions, but I can actually remember this, so I always stick to those choices! HTH