you should not drive for long periods with the light on buy a fault finder for your car witch will tell you the problem cheaper than the garage using thier machine .
the whole point of the light being on,is that there is something wrong with the car,it could be minor,but it could also be major which could cost you a lot unless you take it in and get it looked at,tell the garage to inform you of whats wrong before any work is done,then you can decide if its cheaper elsewhere
you could always take it to a free fault finding garage get your quotes and weigh your options up. to be honest i'd rathere be safe than sorry just in case there is a fault we are not technicians only opinions good luck x