I tried the initial field coding in your tutorial and couldn't get that to work without erroring, so did a bit of Googling and found what I posted previously which got me further.

If I didn't need to try and sort this fairly quickly, I'd spend more time messing around trying to get the right field coding. But I'm really just looking for someone to be kind enough to show me the field coding required to achieve what I need to achieve please. If that's not possible, I'll seek help elsewhere.

Many thanks, Doug.