The UK limits the age because they want doctors to council the pre-16 on sex and other possible solutions like the pill, depending on the amount of sex they're having.
Age Restrictions on the Morning After Pill
Since it's been available to "underage" females in many European countries for many years I have to assume it's safe or they would have banned it, themselves, or at least put age restrictions on it. That fact that they haven't speaks for itself. Do you think Europe is less concerned for it's citizens than we are?
Contraception: buying the morning after pill in Europe