Looks like you're covered on pratchett and tortall recs. I was a big fan of Pippy Longstocking as a kid, but haven't read them since so I don't remember if there's anything you need to worry about in them. I mean, I turned out okay :P

I also liked the Halfway Across The Galaxy And Turn Left series, and Isobelle Carmody's Obernewton series (which gets VERY meaty eventually but I definitely started it in primary school).