For what it's worth, here's some experience from several rides between Bradford on Avon and Telford or Farndon or (mainly) Stockport:
Making it a 300 gives lots of choice (even more, if you choose start/finish points a bit away from home/destination).
Or, plan a more direct route of say 270km, and either ride it as a "long" 200, or enter a 205 section of that as a 200 - adds a sort of variety.
In spite of the attraction of the Severn Bridge, I sometimes used the flat way - Cirencester, Droitwich, Kinver... then avoiding the A41.
Very early starts give quiet main-road options.
Happy Planning!