Rain gardens are very popular in the Seattle area, here’s an example of community driven programs. https://www.12000raingardens.org/
That looks great! Thanks for sharing that. Now I have to see if the UK has these.
I think a lot of your areas have similar weather, I think they would cross over nicely. There are tons of clubs and DIY videos here, this is an example: https://www.bhg.com/gardening/landscaping-projects/landscape-basics/make-a-rain-garden/