I bought the Air Law book from Oxford before I started my training. So yes, you can order at least single copies from the Oxford series. But keep in mind JAA books won't help you much when you have to sit the FAA exams.
If you want to browse the internet for pdf copies I suggest looking for file names like "JAA ATPL - Book 09 - Oxford Aviation Jeppesen - Meteorology.pdf" and so on.