I've tried the range of these, and found they tasted quite cheap, chalky and sugary.
The white one especially put me more in mind of Hershey's disgusting, seemingly chalk-based 'Cookies and Cream' so-called chocolate.
It's not surprising that you found them in Tesco: they're Tesco's own make in any other guise (much like their own-make Red Bull knock-off brand, Kx). Rather than present products 'own-brand' they often disguise them behind a brand name / farm the manufacture out to external generic manufacturing companies, possibly to encourage consumer purchase and thus increase their personal revenue.
Given the price of these Chokablock bars, compared to their similar-priced market competitors, they're not really worth it. If they were cheaper, maybe, but given that, with good shopping around, one can purchase something of a moderately decent quality for cheaper per 100g, I find them overpriced for what they are proported to be.
