Hi,
Have you gone to a garage to get the emissions checked? Just from what I heard, emissions can be a nightmare... a few things contribute to the issue, so you could be lucky or unlucky with what gets changed...
For my previous cars going to NCT, usually drove the car in 3rd gear on the way down to the NCT centre, make sure the engine is "warmed up"... Also, you can buy cleaners for the engines - just add to the fuel tank after putting in some fuel - but haven't used these at all...
Has the car been serviced on a regular basis?