Looking for an old Christmas film - I think it is British, set during a war and a boy loses his parents.?

I am looking for an old Christmas movie (I think it is a British film set during a war) where a boy loses his parents during the war. He writes Santa and asks for his parents back. His cl then goes on a field trip, the little boy and a little girl get lost at an airport and proceed to walk to Santa's house. They enter woods where Ogres live, I think there is also a Fairie (the same actress as the teacher). They find an Ogres house, end up at Santas, sleep in Santas bed and thats all I remember. I havent seen the movie in 20 years and was in Germany when I saw it. If any one has any clue about the title please help me. Thanks bunches.