my cars slowly been getting rougher and rougher when its been cold. When i start it cold its a kind of white/gray smoke from the back, when its running still the black reek though. a few days ago the turbo wouldnt come on to boost, done it once or twice then disappeared, the past few days i wont come on to boost in first or second and sometimes third, been scared to put the foot down properly just incase something breaks. Just come home tonight from a skiing trip and plugged my obd sensor in, was only the other night that the engine management light came on so the fault code i got was PO237 turbo/super charger boost sensor "A" Circuit Low. Has anyone had any experience with this problem before ? thanks

also getting some blue smoke now as well

Sounds like your turbo is about to fail expensively if you don't stop using the car. Get it looked at now before that happens.