Can anyone tell me what this plant is called?

It appears to be linaria, I think. If so, it will look after itself and seed new babies as well if you leave the flower heads on. They can be shades of pink to mauve as well as the occasional white one.

They are not long-lived plants, so the seedlings are useful. You can cut the stems right back after flowering if you want to tidy it up.

Yes I agree with Spritshenry Linaria Purpurea.

I have this growing all over the garden, as Spritz says it will look after itself. Just pull up or pot on the ones you dont want.

I have it too, i love it, it pops up all over i just pull out the ones i don't want, there's pink and purple

I love plants like this - apart from being attractive, they are so generous with their offspring and so easy to remove where they aren't wanted. :-)

thanks for all your replies - looking forward to seeing it in flower!