Hey y'all!
A few online resources to help you on your way:
http://www.englishbiz.co.uk/
Once you get past the cheesy lingo-- "this is the biz!"-- this is a pretty comprehensive website.
http://www.gcse.com/english/
I get the feeling that a lot of this site is advice for the "just-squeakin'-over-the-C-grade-borderline" brigade, but there might be something of use for you here.
http://www.bbc.co.uk/schools/gcsebitesize/english/
You just can't beat a bit of BBC Bitesize-- though again, some of the advice is pretty basic. That said, there's lots of interactive features here, which can make for a refreshing change in your revision schedule.
Ther's plenty of other sites-- try typing the names of your texts into Google (UK sites only!) and you'll find plenty of school-based sites that offer extra help on all aspects of your GCSE English Language/ Literature.
Good luck on your mocks!
