Hey all
The issue is sorted now - seems the local garage had a batch of dodgy fuel, that I think blocked an injector. Mine wasnt the only vehicle driving round the area chucking out white smoke like it was going out of fashion....
A quick change of the fuel filter and a bottle of redex type additive in the fuel tank worked wonders - The engine is running sweetly at the minute, no chugging and no smoking!
Hopefully, that's sorted the issue out, without me having to tear the engine apart...
Cheers
MM