my vauxhall zafire 18 comfort 52 plate driving when cold?

Check the coolant temp sensor.
Easiest way is to plug it in to diagnostics computer and monitor it in live-data, but if you can use a multi-meter, unplug the sensor and check the resistance with engine cold, plug it back in and run the engine up to normal running temp and check resistance again.
Resistance should be around-
2500 ohms at 20c.
250 ohms at 90c.

gerber
February 2010