Leaking anti freeze coolant

It sounds like it is a fairly slow leak so driving the car should be okay. Keep the reservoir filled to the line indicated, and watch the temperature gauge for signs of overheating. If that happens, stop the engine, let it cool down, then fill the coolant again. Some small leaks, like a loose hose clamp or rotted hose can become a major leak without warning if that rupture becomes larger or the hose gets pushed off. Some small leaks will remain small leaks for quite some time, but you see how little time it took for it to go from no leak to one that is big enough to see a puddle on the ground.