Robbo, as an update, I followed a couple of procedures I found buried in the forums that have cured all of my smoke issues:
Stage 1 - Electrical Connections
1) Buy some 3in1 or WD40 Electrical Connection Cleaner
2) Take off the engine cover
3) Disconnect the electrical connectors on each injector
4) spray lashings of cleaner into the plug and sockets until your happy they are clean
5) while your at it, do the MAF & MAP and anything else you can see with an accessible connection
Stage 2 - The Concentrated Injector Clean
1) Get a bottle of Wynns Diesel Injector Cleaner.
2) Run your self out of fuel till your orange light comes on
3) add the full bottle of wynns
4) Go and rag the car, enjoy yourself, but dont run out of fuel!!
5) Get a bottle of Wynns Complete Diesel system cleaner or direct rail injection protector etc
6) fill up your tank and add the wynns
7) drive normally and your car will feel, faster, more dynamic and like new! (also no more smoke)
8) if your smoke comes back after the next tank, go see a professional, you have a problem!
After I did the above 2 stages, I blew a 0.94 on my MOT smoke test with no DPF, EGR and an F1 map from AHM
Stage 3 - Optional Intake clean
1) Follow PeteMcKs guide
on how to clean your intake, if its gunked up this will also sort any hesitation / stutter at low RPM.
All three jobs are no more than an afternoons work, will save you £££'s at a specialist and make the car run smooth as!