My temp light comes on straight away when i start the engine.If i drive down the street,stop then restart car again it doesn't come on.Just the first time of the day.It used to be when it was just cold weather but now it's all the time.Is there some sensor i need to replace or something?

It will be the sensor in the coolant expansion tank.

You have to change the tank, which isn't difficult, and a genuine one is around £15

Ok,nice one.Will have a look for one . Cheers