My parents are from Canada, and when my dad was in the Navy in the 1980s, he was deployed to the UK. His biggest story is that they couldn’t buy peanut butter and Kraft Dinner except at the Base, which was obviously a problem. I travelled to the UK recently and asked someone there about those two items. Peanut butter is available now, but not that popular, but Kraft Dinner was unknown and frankly seemed disgusting to…
Boxed macaroni cheese can be purchased at every Tesco as "cheesy pasta".
Judging it to be disgusting I would agree with, but 'unknown'? By no means.