I can shape the filler and get it perfectly flat, I make Michael Angelo look like a vandal, only it takes a LOT of work. Can someone point me to a good resource to swot up on using filler 'more easily'?

What grade paper are you using to get the basic shape? I'm gonna guess your starting too fine.
Rough the shape out with 80 grit on a block, then move down to 120 then 240 and finally 400.
400 grit is about as fine as you need before primer.
Once you have etched any bare metal, high build prime it then flat that with 600 then 800 before paint.
Adam

Yep.. oversight on my part:

Thanks!

was using p180 all the way with filler.
I use 600 then 1500 on the primer before actual paint.
Wish it wasn't so damn cold.. waiting for filler to cure at 0oC is almost futile, even with extra activator.

Hair dryer will get it to cure faster

Avoid a proper heat gub as you can burn teh filler.

Last bit!, oh.. there's another dent I missed/forgot about/has appeared/I made....

Noooo, there is another door as bad as this one though.

Door skins?