Hello and welcome to the forum.
Your nearest launch sites would be on the Trent: West Stockwith (Gainsborough), Farndon (Newark) or Hazleford. See Boatlaunch.co.uk for details.
Tidal section's a bit boring tbh, at least there's no speed limit downstream of Gainsborough bridge. I'm going to try it out to the Humber and see what scenery the Ouse has to offer. Upstream to Torksey Lock you can go all the way to Lincoln.
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