Me again! Sorry for more threads but I've narrowed it down to these three and in 6 days time you'll be rid of me 
Live in England, half Irish baby. These are the spellings we would use (not Caolan as I think it's too confusing here and I think Killian looks too much like 'Kill')
Cillian is pronounced Kill-ee-un
Caelan is pronounced Kay-lun
Keelan pronounced as written
Thanks and please be kind as we have really struggled to come to a middle ground on names.