My school you picked one subject from each group (with each group containing the previous groups) for your three options. The year above me's group A was they had to do a Language - French, Spanish, German, Latin or Computer Science (which they counted as a language that year, strangely). I got the choice of a language (not including Computer Science) or Geography/History, and Computer Science was only in Groups B and C.
Apart from courses that didn't run due to low take-up, I don't know of anybody who didn't get to do their options due to timetable clash - I didn't know anyone who wanted one of the scrapped options either, though I think there were one or two.
Incidentally Spanish was quite popular in my school, possibly though as the teachers taught Spanish and French or German and French, and the German teachers weren't very popular.