I thought I replied earlier but doesn't seem to have appeared. No loss as no great experience to contribute.
First: respect for growing up there on your wet and windy island.
I've got a middling lidded bucket and drown couch grass, dandelions etc in there. It gets left til I remember - weeks at least - and then ladle it out into milk containers; still got some left from last year.
Doesn't take long for it to get pungent. Really clears the tubes but I don't mind cos takes me back to working on farm when I were a lad.
Also got a small comfrey bed so in a semi organised fashion I'll do some comfrey tea and accumulate the weeds separately. I've picked up the notion on here somewhere that the usual weeds, especially nettles, are higher in nitrogen and comfrey is the one for potassium.
Maybe someone knows: how long to drown the plants so any seeds are killed
does the fertiliser value of the tea decline with time
what do the usual random collection of weeds contribute to the brew - mostly nitrogen or more balanced. I'll still brew it up but would be interesting to know, frinstance, which crops to shower with it