As mentioned, the Asda store in Essex near my parent's weekend retreat doesn't stock it. Neither did the Asda near Kingston.
We stocked up some months ago from the Asda in Colindale (they only had the 60ml size) and were just down to our last bottle when my parents offered to take me shopping.
As they have a car, we went to Oriental City in Colindale (closing down in May - it shows) and, just to get more Cholula, we went next door to the Asda.
Lucky for me Cholula was on Special Offer - so just 78p a 60ml bottle.

We didn't quite clear out the store but did take 20 bottles - 19 of which I've kept. We calculate (based on previous, modest, consumption) that we have a year's worth.