Type 'overwinter Canna' into the search box top right, and you'll get several answers.

If its the basic Canna indica, commonly known as Indian Shot, mine survive outside, even through last winter. They're in a border, southfacing, and have multiplied to the point where I have to keep digging it out. On the other hand, if they're Canna generalis hybrids, such as 'Wyoming' these need removing to a frost free place. Can't say what applies to you Guest - although you've said you're in the UK, no idea where, and that makes a difference.