This weed has been growing in my south-facing garden (London, UK - within 0.5 mile of woodlands and wetlands) for a few weeks now. It started as a low-lying cluster of broad leaves (a bit like a flat cabbage) but has now grown into a monster so I need to dig it out before it takes over my rose bed. It looks quite nice, broad green leaves and delicate blue flowers that seem to attract quite a few bees, and it even smells nice... but it's got to go!
If the leaves are unpleasant/rough to touch, it's Pentaglottis sempervirens, common name green alkanet, see here https://www.rhs.org.uk/advice/profile?PID=1001. Its very common throughout most of the UK, particularly in the south.
Despite the attractive flowers, extract it asap - it puts down deep roots which can be difficult to dig out completely - it will regrow from any root left behind, and it seeds itself freely.
Can it be field forget-me-not, Myosotis avensis? Here some info from wiki, to check if it matches.