> What really would help me - and i struggle with this - if i have clear priorities in my head - what I want to achieve in the 'extra time' that I have got. The clearer the goal, better the results.

I suffered with the same thing. I started using dynalist (https://dynalist.io/) to list down whenever i felt like i wanted to do something. Later when i have free time, i just go to the list and see what i can finish in the time i've got. It offers a very intuitive interface to map/organise ideas. An alternative to it is Workflowy (https://workflowy.com/).