In answer to your question - Gosh, I haven't been to the Lakes in the Autumn for years, so can't really help. But a great place in August so I expect even better now was on a walk between Monk Coniston (north east end of Coniston Water, a currently being renovated walled garden) and Hawkshead. Another good place was Dodd Wood at Bassenthwaite. But to be honest it will be so wet an d lush there I expect you will be in luck most places.
Have a lovely time - I am rather envious. I would love to go myself this time of year or winter for a change of scenery and all those photo oppertunities

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