Following on from KenGordon's earlier post.
I am a member of a BSAC branch. A large part of our branch membership have or where originally trained by PADI. (My own original qualification was PADI OW, much later I also did the PADI DM.)
Whilst it is perfectly acceptable to be a branch member and dive on their PADI qualification. Most (all) have BSAC qualifications, because it is effectively free (other than the course pack), to take the next appropriate BSAC qualifications because the branch instructors teach for free.
A reasonable number of these PADI members, view their diving as PURE recreational diving, no technical diving. On branch 'recreational' trips, they will probably do dives over the weekend that require compulsory staged decompression. They view the dive as a recreational dive, it may be 5 minutes or 15, much beyond that people will start to view it as a bit more serious.
Scapa flow is seen as a normal branch destination. Most branches would put the experience requirement as Sports Diver, although this precludes you from some of the deeper sites. You can dive the sites as No-Stop dives, very few ever would. Generally Scapa is a two sites a day destination,
Capital Ship in the morning,
Block Ship in the afternoon. The two dive a day approach, keeps DCI risk low. To be honest, two dives a day is normally enough for anyone, when you take into account the environment (above and below the water) and the 'work' involved.