Most people do the exams in two sittings. The only difference is what exams get done in what order.
My understanding is that you MUST do the exams through an approved ground school, that is follow their approved syllabus and attend a revision course before the exams. The ground school also sign your exam application form so you can't sneak around the system. Best way is to talk to a couple of the gound schools. I used Bristol. Very happy with them.