I think the biggest issue for the "Central Coast" and "North Coast" areas of BC is the lack of current stations, Primary and Secondary. So Murray, you pretty much have to use the CHS Sailing Directions:
Canadian Hydrographic Service
I see these are now downloadable. They will indicate the currents through some of these areas, offset to other tidal stations, usually Prince Rupert. The Douglass Books also reference these.
The other major issue relates to poor charts in the areas. This is particularly bad for the West Coast of Haida Gwaii (WCHG). The Hydrographic Service is working through this but progress is slow. We found that use of a radar is very important going through small passes as in some cases the shoreline is not marked correctly. Murchison Anchorage is one such area that is has poor surveys and requires careful navigation. We watched the AIS target of the CHS vessel "Otter Bay" travel over "dry land" on the chart as it left the anchorage!