Am I right in thinking that Kara and Artem are the only couple ever to win without receiving four tens at least once?

According to Wiki, neither Darren or Natasha scored a forty. I couldn't be bothered checking beyond Darren's year, but you might want to.

I think Alesha and Matthew may also have not had a 40 - can anyone confirm?

I think I have seen that mentioned as a fact here, but wiki has the breakdown for each series, if you want to check.