Just printed it at A1 on my plotter at work and the qulity is excellent! - can send you one if you waould like.
Just a couple of comments:
I would have pointed the Runcorn Arm at the MSC rather than the Weaver
The key states that a Circle is a Canal Junction but you have several on River Junctions (Hull, Avonmouth, Weybridge, Tewkesbury etc - perhaps 'Waterway Junction'
You have the Junction with the Regents and the Thames as Limehouse Basin whereas I would j=have thought that Limehouse is a more acxcurate description.
Just my two pennuth
Tim