Unit name please

[Yogi bear]

Anyone know what they call the water outlet from the cylinder head which has the vacuum pump attached is called.

this is on my 2010 2ltr cdti sports tourer.

also, where can I get a new metal gasket for this unit as mine leaks like a sieve after the thermostat opens. It’s not coming from the vacuum pump as some  u tube videos suggest. I have back flushed the rad, engine block and heater matrix and have no other leaks. Any body got 5 litres of unleaded and a match maybe. Suggestions please.