Thanks for the advice (need to change my email address so didn't realise anyone had replied) - in fact I rang their helpline today and it was no problem to book there and then at £25 for the single sector, what it says on the tin.
Though I do find myself getting slightly embarrassed on Stelios' behalf at some of the unwarranted cynicism against EJ expressed on this thread, given the ease of booking and the friendly, good-natured young Espagnolese on the phone (as it sounded like) that made the call even a pleasurable experience.
