For edexcel C1, C2, C3, C4, M1 and S1 will all be available in January and June.
HOWEVER: Your college/school may or may not choose to offer them - you'd have to check with your exams officer. My college only organises S1 in June for example.
You will also find that some papers are on the same day and you'd have to take them one after the other (no break) e.g. C1 and C2.
The edexcel timetables for 2009 are here: http://www.edexcel.org.uk/sfc/fescho...-keydates/gce/