Hi Ian, No the head gasket would not be touched during a cambelt change, if the head gasket has gone take it to an independant garage and they can do what is called a "sniff test" it's a chemical that changes from blue to yellow if the gasket has gone, was the cambelt change done as a routine maintenance or was it from a belt failure as with a failure there is always a possibility of internal engine damage!
nigel, August 2008