[Gingerbread Latte]

Primark has cheap white shirts and I saw some tartan skirts in there today so if you went there it'd probably cost less than the schoolgirl outfit from ebay

Then just head to Home Bargains, Poundland or whatever bargain shops you have there and grab some fake blood and greenish face paint to make the look complete. If you wanted you could get some of those contact lenses that make all your eyes white, I think that would look pretty cool.

Hope this helped!