why is my temperature gauge in the red when the coolant is at the correct level?
 

2001 TT - on the diagnostc the coolant temp is 90 degrees c. After 5 minutes the gauge goes over 90 then after 10 minutes driving it is in the red and the warning light comes on

That'd be a good question for the TT forum, rather than the D2 forum where's is currently posted. However when I had a problem like this in another car the water pump impeller had come loose. It could also be a thermostat problem. You'll want to see if your radiator is getting hot or not and see if the fans are working correctly. If the water pump is seized up this could also take out your timing belt and that'd be expensive.