"Oh Shit" moments...

Kensal road.
Truck pulls half way out, looks at me, I wave for him to go back and comes out all the way blocking the entire road.

At this point I'm 20 metres away, it's wet and I'm hitting about 20.

I try my best to stop but just end up doing a 2 wheels skid and fall over hitting the front of his truck.

Fucking hell my knees and shoulder hurt.

Sounds like he mistook your "go-back" wave for a "go-ahead" wave.

I know people telling you to be more careful gets old pretty quickly, but it's best to assume that the average driver really isn't going to be doing everything they can to ensure the safety of cyclists, and to act accordingly.