Have drawing floor plan to be put into a software I can use

I have a warehouse with 2 mezzanine floor. I have the drawing on paper (enclosed) and need to be transferred into a simple software so I can play with it to calculate what racking/pallets I can put into the warehouse.
I need to fit on A4 format so I can print it.
It is essential I can use the software after the job for free for unlimited time so I can paly with it.
Doesn't need fancy 3D or 4D capabilities (even if it is fine to have it)
I have enclosed the floor plan I have at the moment and I will had the dimension to it so you can do it on scale (the warehouse is 16500 sq. ft. on ground floor). I am not concern about the height as we store nothing above 2 meters.

Please state your budget in the offer and what freeware you will use