This is gonna sound "odd", but how much do you really need to be off-road? I only ask because somewhere like the Western Isles (Barra, Uists etc.) would provide reasonably easy road riding but with very little traffic.
You suggest you'd like to be "away from it all" but that really means taking tracks and paths into areas with little or no accommodation. Typically, these tracks and paths are therefore not ideally surfaced so you need to accept there will be a bit of climbing and usually some sort of "technical" skill involved.
What sort of duration were you thinking of?