I like [name_f]Iris[/name_f] on a boy! I think with you being in the UK, you could get away with it quite easily! I grew up in NZ with a boy called Purple and none of us kids ever questioned it 
[name_f]Iris[/name_f] can totally be a boys name!
I think the sound of [name_f]Iris[/name_f] is quite unisex but as it’s been an established girls’ name for so long, I’m going to go with no - I don’t like it on a boy, at least not in the first name spot.
I have no objection to it personally. But it would be unusual in broader society. I really like [name_m]Idris[/name_m] and [name_u]Ira[/name_u], though. And [name_m]Ivan[/name_m] and [name_m]Ian[/name_m].
No, I wouldn’t do it. [name_m]Idris[/name_m] [name_m]Apollo[/name_m] is fantastic. Or [name_m]Apollo[/name_m] as a first name would be great. [name_m]Ivo[/name_m] is cool. [name_u]Eden[/name_u] and [name_u]Wren[/name_u] are only used for girls around me, and while unisex in theory, they could be hard for a boy to wear in real life.
I love that you’re considering [name_f]Iris[/name_f] for a boy!
I actually really like it, and I’m not crazy about [name_f]Iris[/name_f] normally. It’s certainly a striking and daring choice for a boy, but in terms of sound, I absolutely think it works. The combo with [name_m]Apollo[/name_m] is super-cool.
BUT this is my opinion, as a twenty-something name lover and feminist. The issue should really be whether a boy or man would enjoy being called [name_f]Iris[/name_f]… I mean, he absolutely should - it’s a lovely name, the flower is beautiful and the goddess is a nice namesake, it’s a great statement of gender equality, etc. etc. - but I suspect that he might find it at best frustrating, at worst downright difficult to be a male [name_f]Iris[/name_f] in the society we currently live in.
It’s a real shame, and obviously if it’s ever going to change then we need people to be prepared to call their sons [name_f]Iris[/name_f] or [name_f]Rose[/name_f] or [name_f]Ella[/name_f], just as girls are frequently called [name_u]Dylan[/name_u] and [name_u]Hunter[/name_u] and [name_m]Wyatt[/name_m], but it would make your son into a trailblazer before he’s even walking and talking and I’m not sure how many parents (or children, given the choice) would go in for that.