private exchange Irelend, England, Wales or Scotland

hello
we are looking for a family in Irland, England, Wales or Scotland where our daughter Emma could stay.
Either only for a few weeks in holiday, or for a term or for a whole year.
Emma is 14 years old and in 9th class of a private grammar school.
We would also welcome a student in exchange.
We live near Frankfurt am Main.
maybe some one has informations as weil for private exchange.
thank you
Waltraud