Thanks for your input guys. I still have the fault, I'm just living with it for the time being. I can confirm it's not down to an earth, the dpf or the egr. The dpf has been cleared out from "94% heavy clogging" to "11% not clogged" and the egr is now working as it should. And the p2009 flow shutter valve fault is apparently down to the new plastic manifold which doesn't have swirl flaps so bringing up an error.
After discussing it with a few alfa owners, I suspect it's down to the fuel pressure regulator/sensor which appears to just be bolted on to the end of the fuel rail. It just struggles the first start of the day, the colder it is the longer it takes to start, and when it does eventually start, a huge plume of white/grey smoke comes out of the exhaust.
Can I unbolt this regulator myself? I know it's riduclous pressure, but is there a way to depressurise it? I can't bring myself to spend money on labour for something so accessible in the engine which looks to be attached by a tightening bolt.