According to the online BA schedules "you can access information up to one year in advance", but I've just tried to look up the CPT to LHR timetable for October 13 (2010 obviously) only to be informed that "The departure date you have entered is not valid. Please change it" .

In my opinion another annoying case of "how difficult is it to get it right". I suspect that it means one year, but not including the current month.