Got a PPI on a 330CI that i loved, thay suspected head gasket failure, HELP

[Jamaican]

Got a pre purchase inspection, 2 mins in to test drive coolant light came on and the car was leaking coolant. The owner kept a botthe of coolant in the boot, the mechanic then removed the rad cap and there were bubbles in the rad.

He then said that he suspected the head gasket was blown or blowing. I do not think he was a BMW specalist, but what do you guys think? Here is  apic of the oil cap.

 

Should i take a punt on it? Also when moving into reverse there was a clunk (auto)

What do you guys think? The car was 1.3k