A few weeks ago the engine warning light began flashing amber on our 1.25 Fiesta mk5.  I checked the codes and was told there was a misfire on cylinder 3.

Pulled the leads from the plugs and splashed liquid everywhere, took a look in through the holes and saw the sparkplugs were swimming.  Poked in some kitchen roll to soak it up and the liquid came out pink, the same colour as our coolant.

A little googling suggested it was the core plugs so I ordered a set and they finally arrived today.

Following along with a youtube video I drained the coolant and popped the rocker box cover off.  This is where things get a little odd.  My core plugs look fine.  They're nice and shiny, no signs of corrosion or holes.  I'm not sure what to do now.  Should I attempt to replace them anyway (not sure how, I was assuming they'd be corroded so I could whack a pry bar through and lever them out) or is there something else I could check for now everything is open?

Hope someone can point me in the right direction.

Could be head gasket. Sorry

What does engine oil look like pull out dipstick if theres water there it'll be streak with white/grey emulsion

Just checked the dipstick, no white/grey emulsion.  The oil is very, very dark though.  If I get to the bottom of this I think a complete oil change is in order too.