Try not to worry too much about mocks - there's still quite awhile left until the real exams. I would suggest talking to a teacher to see where they think you're at (a lot of teachers mark mocks really harshly, and you might actually have done better than you think - if your mock papers were actual past papers, you could look at grade boundaries, as your school might use inflated grade boundaries) and ask for advice on how to improve. Maybe spend five or ten minutes a day doing work on a topic you don't understand as well as you want to. As for whether you'll have another set of mocks, it really depends on your school. It's likely you'll improve from your current grades - we were told I believe (though my memories of GCSEs are a bit hazy, since I'm now in uni) that it's not uncommon to go up two grades from Christmas mocks, and it's definitely possible to improve further. Good luck, and hopefully your GCSEs'll go fine - it sounds like your doing a great job in most subjects, so make sure you don't lose sight if the overall picture, and if the worst comes to the worst, the college may well accept you anyway if they only recommend those grades for Physics and Maths.