Last night's BIC did go more smoothly, once I realised it was OK to cringe at what I was producing.
And looking over the stuff I'd done on the weekend, it wasn't as bad as I thought. Well, maybe it was, but I've been able to work with it a little, improving what I had, with the added bonus of having a nicely fleshed out scene sitting on my computer.
I've also starting taking notice of how I write in other aspects of my life - my blog, emails, reports for work (and, yes, posts on this forum too). I've noticed that I usually have an idea I want to get out, but I spend a decent amount of time playing around with work choices, sentence structure, paragraphing etc. If I do it for measly 50 word emails, I should probably expect to write my novel the same way!
So my aim for the first draft is: write each scene as I want it to happen, and get to the end of the book. Then it will be time to fiddle around with what I've written.