LT
I think there should be no problem, you can go for it.
Here a few link about company policies. Pretty much the same.
British Airways - Children travelling alone
Alitalia - Unaccompanied minors
Unaccompanied children
Unaccompanied minor service - KLM.com
I wish your kids a pleasant journey and a nice stay with the UK side of the mafia.
The day you wish them to taste the Italian side let me know and we'll arrange a UM group trip to my homeland
Ciao
Ulxima