My favourite of the kids without parents around type books as a kid, was
Homecoming. Followed by
Dicey's Song Even now I get a lump in my throat at the second title, though Homecoming was the best of the two.
http://en.wikipedia.org/wiki/Homecoming_(novel)
Was published when I was 11, and I think I read it when I was 12.
Heh. I hadn;t realised there were more in the series. I fell off after Dicey's Song.