Valve Taps!

A very unhealthy noise. I'm guessing my anti-freeze (which seems to be leaking somewhere) is leaking into the motor and a head gasket has gone bad. But i'm getting valve taps as a result. Tomorrow when I change my oil i'll find out if that creates a temporary fix until I can replace the gasket (if that's even the problem). Plus I have to keep an eye on my coolant bottle since it seems to be emptying, but still keeping the radiator full.

Anyone else have this problem before?