After playing with pen and paper (and forgetting or losing lists and notes) I’ve figured out digital is probably best for me. Whilst Apple Reminders is ok for iPhone it’s terrible on Mac so I’m back to Things 3.
The first thing I did was actually go back to pen and paper and write everything going around in my head down. Once I had this I sat down with my Mac and started to put some structure into these items.

You can see I’ve created an area for each part of what I want to organise. Under each of these I have separate projects like this:

I then use the Today and upcoming views to keep on top of things along with reminder times so that important items have a due time along with a due date and I get a notification.
My favourite bits of the app are the widget, integration of my iCloud calendar, pay once (no monthly subscription) and easy dragging of items in the today view so I can get an order. My least favourite bits are lack of accessibility options (like changing font size) and not being able to hide repeating items. Overall though I’m starting to accept apps aren’t going to be 100% what I’m after so I’ve settled on the one that matches the most of my requirements.