its a good start but will have to wait and see how it proceeds. for all the hype in the cannon about slytherins and cunning they seem to possess none of it.Ginny or any of the other characters like harry,ron or hermione being good fighters is a debatable issue.harry for one is a damn lucky idiot.
looking forward to read some more original stuff like this.
hope the characters in your fic have what the cannon lacked sorely ie,common sense...try different allies,ships,methods and whatever else your mind can come up with
an organised group with proper weapons can take out voldie easily...
the main issue in canon was that all action was confined to the UK...do you think that none of the other countries in the world have never faced dork lord problems...that part of potterverse along with some other stuff was just pure dumb
hope you try to write something different
cheers
dexterz