Laying New Floorboards

Hi all,

I have a room that is being renovated, currently it is back to the brickwork and joists. I have new floorboards to go down and have laid them down loose with a small gap at each end ~2 - 5 mm.
I am wondering a few things now, as I am not sure what I have done is completely correct.
Firstly I am wondering if I should have put up the plasterboard first or made allowances for it, as at the moment once the plasterboard goes onto the walls lifting any boards in future would be made impossible as the plasterboard would be over the boards.
Secondly is this enough of a gap at the end, when looking some sites they recommend 10mm at each end, to allow for any movement, would this be from the brick or in from plasterboard (if the second then skirting would hardly cover that and leave a risk of a gap)?
They are cut, but I can obviously cut more if needed, however boards are not cheap and while I can cut then shorter I cant make them longer. I want it done right, so don't mind making changes if needed.

Next comment is related to securing, I have a preference for screws over nails so I think this is the way i'm going, however what would anyone advise? I was just thinking standard gold screws although I'm not sure of the sizing to use (floorboards are 6x1"). Also not sure how they would look, or if the heads would potentially cause the wood to split.

 

Thanks, I'll definitely get those screws if they can be used "top down" the boards I have are not T&G but flat edged, I assume they would still work...shame as I see no way of hiding the screws.

As for the lifting to clarify a single floorboard runs the entire width of the room, so it will be covered at both sides. I don't see how they will be lift-able without cutting in the future (if required) - which I want to avoid if possible.