AS/A-level Physics External Candidates

A question moreso regarding the AS/A-level physics (AQA) (Syllabus A) itself.

Say for example, as an external candidate, I was to take just the written exams in say, this June (2014), so Unit 1 and Unit 2 for AS AQA Physics and not do the practical component (since this school don't offer the practical component, since they can't accommodate any more students this summer)

Would i be able to continue next summer and finish off the AS by doing Unit 3, the practical element? Would this still count towards the AS qualification?

Weird question i know, but I wonder with the changes to A-levels whether the A-level is still modular, i.e., taking individual written papers to together, or separately to still count for the overall grade.

Any help would be appreciated, thanks.