As security, additional the 5 or 6 lever lock / hefty padlock, may I advocate fitting hinge bolts?
If the hinge pins are externally accessible, driving out the pins would allow the door to be lifted away from the striking plate. With hinge pins, this is much less of a possibility.
My door is a recycled fire door with a 6 lever mortice lock, but the hinge pins are just visible, externally. So anyone feeling strong could obtain entry in this way.
I made my hinge bolts by turning the heads off No12 woodscrews. The screws were screwed into the wooden door, using a drill chuck. The door was then partly closed so that the pins marked the door frame. Holes were than drilled on these marks, to act as sockets for the pins.
If you have windows, cover them, internally when not in the shop. If the lowlife cannot see what there is to steal / vandalise, they will look elsewhere, certainly if entry is going to be difficult.
Howard