If you look at the key at the bottom of the page, you see he has hardiness symbols as one, two or three blue spider icons. In general for suburban SW London, I would look for a variety with at least one blue spider (hardy to -5), assuming you aren't in a frost pocket. In fact the only one he sells which he claims to have any hardiness to that level is Musa sikkimensis.

Musa basjoo is the other well-known (root) hardy banaba, but he's not selling it.

To choose something else, you will have to know your garden conditions very well and hang around on exotic plant forums where lots of banana growers hang out, who have recorded what is necessary to get particular things to survive. I'd have a look through the posts on the (now closed) UKOasis site - lots of posts about marginal bananas there. Growingontheedge is the successor site, but it hasn't been going very long.

People don't usually grow these plants for the flowers. You have to overwinter the pseudostem for several years to get them to flower, and then they die after flowering. People usually grow them for the leaves, and maybe don't mind if they resprout each year from the roots.

To avoid the nasty-bugs-when-small phenonmenon, consider buying a reasonable sized plant rather than seeds. I don't think bananas are the easiest thing to grow from seeds. In fact, cavendish bananas (the ones we eat) don't have seeds, they can only be vegetatively propagated.