This Inst of Govt article was from 2015, but very interesting analysis of what happens re confidence / NC votes.
Whether a PM has the "confidence" of the HoC is also about politics, strength in the country, confidence within the party as a whole,
not just numbers of MPs
www.instituteforgovernment.org.uk/blog/votes-confidence-queen’s-speech-and-fixed-term-parliaments-act
A defeat on an explicitly worded vote of confidence, and the failure to achieve a second vote of confidence within 14 days, is one of only two ways in which an early election can be called.
Confusion exists about what effect this has on other worded votes of confidence or critical votes such as the Queen’s Speech or a budget.
Certainly they don’t trigger the 14-day period – the Act is clear on this – but ought a government resign if it loses any of them?
In practical terms this is about whether a government ...... should resign if it fails to carry a Queen’s Speech,
or insist that without a formal FTPA worded vote of confidence that it will continue.
Or, because the Act does not require resignation, could a government defeated on one FTPA vote of confidence
stay on through the second vote of confidence and get a second election instead of passing power to its opponents?
Both questions are matters that are more about what will look legitimate, fair and politically viable, rather than a question of legal interpretation.
They go to the heart of past convention of when and why governments resigned when they lost.