In reply to Xharlie:
I think the replies that you've got show the problem - there's not "normally" a place for bike spaces, as it depends on the train. On some they're in a carriage (somewhere), on others (East Coast, for example) they're in the Guard's van. So you're right - it's a bugger to know where to stand, especially as there's usually a 6" high picture of a bike by the door, completely covered by people crowding to get on.
They do say "arrive early and consult station staff", but with the exception of East Coast and Virgin (in my experience) there's rarely anyone from the train company on the platform until seven nanoseconds before the train arrives.