That depends on the school - we would simply treat that as private tuition. We often have people from other schools and many self-certifiers. What you suggest is possible, but unless you are able to self-certify by having an ATP and PIC hours on multi-crew aircraft, you will need an ATO sign off anyway, which means using their study material and consolidation anyway. Some schools require you to do all the progress tests before you turn up for consolidation, we don't require that - in fact we recommend that the classroom stuff is done earlier rather than later, i.e. definitely not at the last minute. You mentioned 16 hours.... ?
Phil