We have just done another section from Wakering to near Tilbury
It was meant to be Tilbury but we were frustrated by high tides. The Thames Estuary Path guide says that such occurrences are extremely rare, but having been there I would recommend that people assume that any Spring Tide (full and no moon) with cut you off!
Most of the route was marked up as England Coast Path so I expect official opening in the next month or 2. A section at Fobbing Marshes is not open yet but ohterwise it is all there