Thankfully I don't have hogweed. I've inherited a few nasties but nothing I can't live with or deal with. I have spent days digging out couch grass but I now just accept it. I had barrel loads of alstormeria but got rid of most of that and I"ve only got a tiny patch of nettle which is, at least, the food plant for some butterfiles. Oh and Spanglish Bluebells. That's going to take years to get rid of from all those awkward places. I planted English ones when I moved in but I regret that now since I can't let any of them set seed. I might get rid of them if mowing impacts on the other woodland plants.
Yeah, the Yellow Rattle really does stop the grass in its tracks, even rye grass. I think I'll buy more seed this year then hopefully I can just let it look after itself after that. I have expanses where you just don't see any grass, the speedwell really looks great amongst the yellow flowers. I tried a couple of its relatives, Melampyrum arvensis and M. nemerosum, but no luck with those. I haven't had any luck with Eyebright either, I don't know why since it grows locally. I'll try again this year though with that. The toothworts flowered this year on the willow, though, that was a treat.