You would not need to attend the Cat 3 course before the BPA course as they are aimed at different sets of people. The Cat 3 (1 day) course is for hobbyists or anyone who purchases publicly available retail fireworks to use for their own private events and teaches them how to use them safely and design an effective display. The BPA Firer training course is aimed at those people with an interest in professional firing, using fireworks only available to professional display companies, and therefore requires a much more extensive course. Both courses give a very good understanding of health and safety considerations, firework types, set up and firing techniques, but the BPA firer course is a day longer and also covers the firing of shells (mortars), electrical systems and so on.