I think you could be right. It would depend on the school and how oversubscribed they were. Trouble is, if a pupil is on the school roll, they are expected to attend that school. If that year group is heavily oversubscribed, they may want the child to be taken off the register. Then of course there is a problem with getting back into that school.
I also think there might be issues with the curriculum since I doubt the foreign school will follow the same curriculum.
Ask the Head.