[John Jarrold]

All you can do is try various agents, and they will make their minds up how they see it. Crossover does happen, but there is still demarcation with a fair amount of the adult and children's fantasy market. Some books first published as adult fantasy are now bleeding into YA - Terry Brooks and Robert Jordan have YA editions from their UK publisher Orbit/Atom, for instance. I think you'd definitely call George R R Martin and China Mieville mostly adult, though, so there will always be those differences, and it will depend upon each individual book