We apply epoxy coatings to various structures including floors for local government etc, the problems with epoxy are the initial bond onto the floor, when new concrete is cast you are left with a surface containing fats, this must be removed and you also need a surface profile for the epoxy to bond to, the only correct way to acheive this is to blast clean the floor using blastrac machines, they remove all the fats, blast in a surface profile and vac all the dust from the surface in one process. It can be very expensive, anything between £6.00 > £40.00 per m² depending on the products specified and the existing floor condition. In a heavy workshop environment you may need to use epoxy screeds which are very very expensive, up to £80.00 per m² but withstand immense amounts of mechanical damgage. If you do not have the means of blastrac prep to the floor you are probably better off just using economy floor paint from any of the main manufacturers, it is economical and easy to repair yourselves and will last similar time to an epoxy applied onto a incorrectly prepared surface.
Wayne