General Intermittent Blue smoke..?

[Wolvesdelivery]

Hi all, I seem to have developed an intermittent Blue smoke issue..?
It can be hot or cold, no particular gear or incline/decline, taking it easy or pushing a little and there are no oil deposits under the car.
What I have found, is the (breather?) pipe which rises from the back of the engine and can be unclipped next to the top of the oil dipstick, is heavily lined with gunk and severely restricts any air/fume flow (if that's what it does) I'm told it may come up from the EGR but ultimately it goes on to join the air-intake at a T junction before the turbo.
I've looked all-over the place, but can't find a definitive answer, can anyone help?