Finally back to the model after a 5 month break.
I removed the battens used to mark out the 5 planking bands after marking the edges on the bulkheads and struggled for a good couple of hrs to get the garboard plank shape sorted out. The garboard plank is the one next to the keel and can be an odd shape (ito width profile) as it twists through a full 90 degrees along its length. It is fitted adjacent to the false keel and if the profile is correct it will provide a natural curving edge for the plank next to it allowing a smooth fit.
In the end I stretched a piece of masking tape between the bulkheads, replaced the batten used to determine the planking bands closest to the keel making sure it never is more than 8mm away from the false keel. I then traced the edge on the masking tape and transefreed the masking tape to an 8mm Sapele strip. I bought the 8mm wide sapele wood strips specially for the garboard plank as the kit only supplied 5mm wide strips used for the rest of the hull planking.