BMW 318ci Coolant leak - Back of the head!

[LeightonBuzzard]

Coolant has been leaking from my car and i am almost certain this is where it's from(small pipe joined to the back of the cylinder head), the level went down slowly and is now very quickly and is evan bubbling up and no hot air through the blowers. I can only see crystalisation there and no actual dampness, access is a nightmare. Its a 4 cyl, silver top; anybody changed this??