Best I can tell from the photo is chickweed and POA Annua. The chickweed is pretty easy. A little Ortho Clover, Chickweed and Oxalis killer should take care of that. The POA Annua is going to be a problem. A few treatments of Tenacity should do it but the seeds it is dropping right now are going to give you trouble for several years. A good pre m plan and careful use of Tenacity should keep it under control.

bumping to see if anyone has any ideas

Narrow leaf plantain, Plantago lanceolata.

Parietaria hespera? The leaf surfaces should be glandular and the leaves should have hairs around their edges(ciliate on the margin). They don't show up in the photo, but the succulent stems do. There's a lot of leaf variation in this species. Some individual plants have leaves that are acuminate, and some can be very oval,round shaped, but your plants have the more standard shaped leaves. If that's what they really are? Lol. I see that Pellitory of the Wall, P. juidaca is invasive in quite a few states over here, fortunately not mine. Doesn't everything imaginable grow on walls in England floral? You could get a lot more vegies by growing them on your walls.😂 I did envy your misty climate when I struggled with growing butterfy bushes. I would see photos of 16ft tall, lush bushes in England, and there would also be pictures of butterfly bushes growing in walls.🤣 I realized butterfly bushes aren't worth the trouble, but if I lived in a warmer climate I would possibly grow unique species of Buddleja. Is Buddleja invasive in England?