Not sure about soil, but if you want some sharp sand for drainage I've got half a ton of it going spare in my front garden (Burghley Road). It'll need bagging up.
Tom, thanks but not quite what my sage will thrive in I suspect...
We have lots of spare soil. However, it has been out in the front garden (bagged) for a while and so it rather wet and muddy. If you'd like it then let me know and we can sort something out. We're in N17, Ruskin Road.
Cool. I will message you and we can work something out. Thanks!