This is a tough question. SP5 (or ST5) is a prerequisite for SA7 and a lot of SA7 questions draw on knowledge contained in that course. Many numerical questions are also from SP5. So you would have to have a very good understanding of it as you went in to SA7. If you believe you can do both in the run up to SA7 then that is fine, but it is quite a lot of work. Particularly if you want to get the numerical techniques under your belt as well.