I like either [name_f]Alana[/name_f] or [name_f]Alanna[/name_f] the best.
I knew an [name_f]Alana[/name_f] who pronounced it similarly to how you’ll be saying it, and her name was often mispronounced as [name_f]Alaina[/name_f]. So I like the spelling [name_f]Alanna[/name_f] because I think it helps clarify the pronunciation. But I have no idea if that would be an issue in the UK.
I think I like [name_f]Alannah[/name_f] best. I feel like it clarifies the PN and goes well with [name_f]Josephine[/name_f] which is also quite a long name.
I’ve always preferred the [name_f]Alannah[/name_f] spelling as it feels more “complete” to me (not sure why), but I know an [name_f]Alana[/name_f] in real life and I’ve always thought the way she spelled her name was lovely too.