On my way to work this morning my heater just got cold half way there ... strange I thought

?
It was fecking cold, so I stopped to have a peak under the bonnet for anything fooked. Sure enough there's mayo pouring out the expansion bottle - FECK !
Checked the dipstick etc and no trace of mayo, also none in the rocker assembly ?... but all the coolant pipes are full with it. I'm pretty sure it's the head gasket unless there's any other points on a golf that could cause this type of contamination ?
Either way not what I needed just before Christmas - Not a happy bunny ! ?:'(