leaky headgasket

My 1985 380SE was in the shop for a water pump and fan clutch, and while it was in, my dad had called them asking them to make sure it was safe to drive (meaning it won't collapse on me - since it has a ball joint that they said to put off for 5000 miles, and after 5000 miles they again said it could go another 5000 - but they took it to mean find every little nitpicky thing). Anyways, so they gave me a list of every little thing wrong with the car and in that list is "left head gasket has a small leak" So my question is, what does this mean for me in the future? What stuff should I be looking for to know when this progresses beyond a small leak and turns into it needs a new head gasket? Even though the mechanic didn't think it was a big deal, would I be wise to fix this sooner than later? And, on a scale of 1-10, with oil change being a 1, brake pad change being a 2, tranny fluid change being a 3, fuel injectors being a 6, and I haven't yet done anything I classify higher than a 6, how hard would it be to change the head gasket myself? Thanks, Richard