OK Only getting around to doing something with this now - NCT retest is next Sunday. I had cleared the codes the last time so read them again tonight. This time I only had errors for the Lambda - so I just ordered that from Micks Garage.

Started to take off the old Lambda sensor and the fecking thing started to bind on the threads:crying:

Got it out eventually though but it took a few of the outside threads with it from the boss. Maybe it's the first day sensor and this is my problem (car has 172K up on it).
Luckily I have a 18X1.5 tap so was able to clean it up. Hopefully this new sensor will sort my issue. Can't see anyhting else obvious when poking around the engine bay - spraying butane gas all around when the car is running makes no difference to revs so I'm hoping there are no vacuum leaks.

My own fault for leaving this to the last minute really but in trying to plan ahead for future tests can anyone recommend a cheap but good (:hehe! CO meter for testing this stuff at home?