depends on the car.
there are many cressies out there that have never busted a head gasket, and there other that do it as soon as you turn the key. so if your looking at one for a daily try and find one owned by some old dorries who only drove to the shops on tuesday and to bingo (there is more out there than you think...)
otherwise, what ever car you buy AND it does happen, dont just chuck another head gasket on as it will most likely happen again. best preventative maintence if it does happen is pull the head off get the head and/or block decked so it has a flat surface and fit a metal head gasket.
unless your running mega boost it wont pop anytime soon.