Hi m8
Before I start i want to make it clear that i am not a mechanic. I am a only a "Hobbiest" car repairer due to the fact that i cannot trust garages as they have tried to rip me off several times.
You say it is blue smoke.
This sounds like oil burning to me.
Unburned diesel tends to be white or grey smoke.
Does it use a lot of oil??
Could be many causes.
Turbo Oil seals. ( I favour this cause it only seems to happen under acceleration)
Head Gasket.
Valves seats worn or valve stems bent.
Piston Rings.
+ many more.
One quick check u can do is look for signs of water in the oil or oil in the water. take off the oil filler cap and see if it has "Mayonaise" on it. also on the dipstick.