I want to be able to 'fill' the map floor with a specific tile which i can replace or swap with others later on as i build my map, is this possible at all?

No, unfortunately there is not a tool for this yet. Once I have some time to improve the Map Editor this is most likely one feature that I will add, or at least some sort of tool for quickly covering large areas with a tile.

Okay that sounds good, it will be very handy to get a map going in short amount of time. May i suggestion have two types fill all and a selection area where you click starting point and as you drag the mouse with button held the square area gets bigger, this would allow for the user to create areas that will have different types of tiles more easily. But you probably already have something like that in mind.

Sorry I did not respond to this and  a couple of other posts originally! I must have missed the notifications. Those are both great ideas regarding fill tools to have, I do have plans to add some functionality similar to that.