What are peoples thoughts? Is it possible to learn plastering to a basic standard to skim walls and the like in 4 days and a bit of extra practice?
I think the 4d course will give you exactly that - a BASIC standard.
I did one of the 4d courses and I think benefited from it. They are all different though, so shop around.
The one I did was a series of techniques taught in a plaster 'bay' - basically an L shaped stud wall section and a ceiling section above the L. It had a little window in the long side with mini-reveals.
In that bay we
touched on: fitting plasterboard onto the studs, scrimming them and skimming walls & ceiling. Dryline over part of it leaving a gap in the middle about 2' square, which we then filled with Bonding next day and re-skimmed the wall. Did some blending in with multi-finish where we re-skimmed the wall except for 1' gap at one end. etc. etc.
Looking back, it got me used to the basics, but no way made me proficient.
for your bit of 'extra practice' -
Since then over 2years-ish, I've replastered most of the rooms in my house (with a lot of help of posted pics & advice from this forum) and only now think I'm achieving reasonable results. The early rooms I did I was pleased with at the time, but now look at them and cringe. I could do better now.
If you're keen, have a go. Really glad I did.
But don't expect professional results from the off. Start small and build up. Gradually you should improve.
The suggestion from some of guys here to offer some freetime for a bit of labouring to a local pro, would have probably helped a lot.
But with full time work and my weekends at a premium, not something I could commit to - but I suspect would have brought me on leaps & bounds.
Good luck!!!!!!!