I have several banana plants in my garden in Southern England. Musa Sikkimensis and Musa Basjoo, 3+m tall at the moment.

Winters are too cold for them here. So either you heavily mulch them and they start from the roots every spring while the stems die in winter. Or you learn how to wrap the stems to protect them over winter.

It might be possible, or borderline to keep them unprotected within London but outside of there and inland temperatures can drop below -5C even in the South.

On the other hand, I think they have started growing tropical fruits like mangos and bananas in Sicily.