palmtree

Welcome from New York City! Good luck with the seeds. I have pretty bad luck growing anything from seeds and banana plants are supposed to be especially challenging from seed.
As for growing edible bananas in the UK I think you will have a bigger problem getting them to grow during the summer than to survive during the winter. In a hot zone 8b you can grow lots of edible bananas such as Sabas Java Blue and Orinocco with some protection as a precaution. In a cool zone 8b Sabas would probably need additional heat to get growing (mine doesnt start growing fast until June when temperatures are consistently near or above 86F (30C). Not sure how Orinoccos handle cool temperatures, but Java blues also like the heat a lot.
Ensetes dont make edible fruit but they do really well in the UK and I have also seen some really large basjoos in climates like the UK also!
Good luck!

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Location: New York City, zone 7b