After finishing the story for the assignment, I now have the urge to Finish More Things, so the creative writing course is doing exactly what I hoped it would, ie made me stop being so self-critical and just write.
The other thing that has helped is the little crocheted cosy I made for the digital kitchen timer. I have a number of timers, but the digital one is really the most useful for longer periods, especially as it has a pause button, so if I've set myself the target of doing 1 hour's writing and I get interrupted by something more urgent, I can pause the timer and then carry on again where I left off.
However... The digital timer goes BEEP!-BEEP!-BEEP!-BEEP!-BEEP!-BEEP!-BEEP!
I'd previously tried muffling it in a woollen sock, which worked well, but meant that I had an odd sock forever sitting around on the windowsill. Then the other day, when I was looking for something else, I came across a little square of crochet I'd been doing. Heaven knows what I'd intended it to be, but with a little modification, it became a timer cosy.
Now the timer just goes beep!-beep!-beep!-beep!-beep!-beep! which is much better.