You need to consider how your new floor with live and breathe. Where you live, your lifestyle preferences and the house you live in will all have more of an impact on this than you may think.
When it rains, not too uncommon in this country (!), the structure of the building is affected. Whilst this does not necessarily mean you place will be flooded, unlike those poor souls in Somerset, it does raise the moisture content of the walls which in turn raises the surface humidity of those structures and so the internal humidity. This, then, is what will affect the dampness of your floor.
Likewise, when the sun comes out, the structure of your building will dry accordingly. Excess moisture was never an issue hundreds of years ago thanks to sufficient ventilation, whereas now with double glazing and our recent phenomena, buildings are now internally suffocating.
This creates a vapour pressure differential between the air and the other construction materials, including your floor.
The clue to controlling the moisture is in attempting to manage your environment. You can control the interior of your building by ensuring adequate ventilation. Passive vents in rooms can ensure damp air can be removed before it wicks into dry materials or condenses onto cool surfaces and aids the growth of moulds.
A thermo-hygrometer will enable you to determine the dampness of your room(s). From this testing you can take the necessary steps to ensure your dampness is managed best as possible.