Around 20 people a year die of unintentional carbon monoxide poisoning in England and Wales, and 68% of those deaths fall in autumn and winter – the seasonal split is the “bringing it inside to keep warm” mechanism showing up in the statistics.
UKHSA advises taking an alarm when camping, because CO can enter a tent from a smouldering barbecue outside it. The full page is here and it carries no affiliate links, as none of the safety reference does.
Any alarm certified to the current standard will do. The cheapest one you will actually pack beats the best one left at home.