how difficult is it to fit new door pillars to a series landy. Just been rubbing mine down for a paint job and realised the off side one is rotten. Got access to a welder but im not a specialist just a below par potcher.

I take it you mean the bulkhead pillor
It's been a while but I seem to remember they not to hard
Welding is all about perpetration. If all the surfaces are nice and clean and meet together well then the fitting and welding part is easy
If you chop out the old one and just stuff the new part in the gap then your asking for trouble