What do you love? Wine? History? Beach? Mountains? That's the real question because you can bike tour anywhere. Answer that one and you'll know where to go.
My wife and I did our honeymoon from York to the Lake District and up to Edinburgh over 2 weeks. Took our time, saw the sights and enjoyed the scenery. Art is a big draw for my wife so we saw the sculpture in Grizedale Forest and there's plenty in Edinburgh.