Hi Jaykaty - this is a very good time to move plants. The soil is still warm, and (if your soil is like ours), quite soft after the recent rains. Good luck!

Thanks for your answer Shelia, I'll follow your advice. Unfortunately, although I'm in Hertfordshire too, we haven't had much rain here yet and the soil is very dry, so I'll make sure I water it well before and after I move it.

Good thinking. Come to think of it, our soil is still quite dry in shady borders, but I was weeding this morning in a sunnier, more open patch and it was fine :)