I thought it looked like a Curry plant in the top pic but WNI called it right, i think: lavender it is. Maybe consider clipping it back as the stems look woody and it will become leggy, overshadowing the fuschia in front over time. No knotweed, but that plant has a runner-root, sending out shoots along the line of least resistance, common alongside railway tracks, so i'd pull the buggr out if i were you. Looks like you've got plenty of buttercup along the ground, too. Don't let it get out of control or soon you'll have nothing but in your garden.
Forget-me-nots have a large green head of leaves over winter and will soon show bright flowers in spring, so i try to pull 'em in autumn to avoid having them all over the garden. Damned seeds stick to anything and spread like plague. I don't see any in the pics.