I have put them in the foreign section, because I am not sure they are a uk release, but anyway...
There is no biscuit, it is wafer, mixed with stuff, you can either have a caramel one, a cream one, or a machiatto one ( coffee).
They are nice, but they are triangular and not really a twix, if you see any, grab one and give it a go, they are worth a good try