GCSE Product Design exam 22/6/15Watch
For the manufacturing side you'll need to revise different tools, manufacturing methods, manufacturing aids (jigs, moulds, templates) and it wouldn't harm looking at CAD/CAM either.
Looking at packaging is also beneficial, especially some of the labelling and branding. You may want to look at the way packaging can stand out e.g: foil blocking, female/male embossing, panels.
I'd also suggest going through past papers, as they are generally all similar to one another each year so will give you an estimate of the types of questions/ grade you may achieve!
You could also revise safety aspects, environmental issues, quality control and human factors in design (ergonomics and anthropometrics)
Best of luck
Read spec if not sure