We did not plan to study abroad from the very beginning, but my wife was transferred to work in Madrid, and a year later it became clear that everything was serious and there was aquestion to move. We have a 8 years old son, he just went to school, so we had to transfer him to a foreign school. Everything went well, we have already been studying in Madrid for 3 years (the school of King's College Madrid Soto de Vinuelas).
Of course, the main difficulties were studying the language - Spanish. But thank God that the child went to the primary classes because of age - later, I think, it would be much more difficult to switch. The school organizes additional courses of Spanish and English - we regularly attend all classes (took a intensive course), and the school program itself is not too complicated, so we have time to study ordinary subjects and Spanish.
I am glad that we picked up the school correctly: the Smapse consultants advised us to choose international schools. There are many foreigners, therefore the administration and teachers always take into account that children can not ideally know foreign languages. Basically, teaching, by the way, is conducted in English, which is a bit simpler (we had a kindergarten with English lessons for kids - songs of all sorts, rhymes, so we had basic knowledge).
It's much easier now: new friends have appeared, there are no such large gaps in the language (only certain terms cause difficulties, but the teachers explain everything in detail). We are satisfied and have calmed down a bit, for which many thanks to the company Smapse: we are still assisted in certain issues (documents, possible transfer to other classes or to another program, etc.). When you feel professional support in such an important matter, everything goes on easier, psychologically as well.