on my way to santa pod today my car overheated down to a failed fan switch how likely is it that the headgasket would have gone? i didnt take it up the strip to be safe. there is no somke or nothing at the moment. is there away of checking i heared you could get something to put in the water and if its gone between the water jackets the water will turn a different colour if true where can i get it from advice welcome thanks.

its a group a one if that makes any differance.