Head Gasket?

I own a Renault Clio Dynamique Billabong 1.2 2003 mge is 52,000, Last week it started to judder like it wasn't firing properly, the next day the coolant light started to flash, i checked my coolant level and its was on the min line. I topped this up and all appeared fine.
That afternoon i drove approx 60 miles and everything appeared fine, as arriving at my destination the juddering started again, i checked the oil level and its fine so i removed the oil filler cap to find chocolate spread like substance around the hole. Carefully i drove home again and for the majority of the journey the coolant light flashed, it wouldn't go any quicker than about 60 mph.
I have been advised that it is the Head Gasket, whilst looking on line for a replacement i came across a couple of forums and 1 said if most of your journeys are short then the problem could be a build up of moisture thats not boiling off, how do i check ?