Perfectly good advice and I certainly wouldn't fly at levels where I thought I might encounter ash but this is certainly not advice not to fly.
150commuter, I'm sure you wouldn't fly at levels where you thought you might encounter ash. How would you know which levels you might encounter ash? That's not a loaded question, as there may be a source of info I've not found. But the met office are showing a danger of ash from SFC to FL200 at present, and other sources I've found say that dangerous levels of ash may not be visible even in VMC.
wsmempson: agreed, the only reference I can see is in the Form215 info where it says "VA - check advisories, VA SIGMETS, ASTAM and NOTAM".
Which reinforces my comment to 150commuter. We are told there is ash between SFC and FL200 over the UK. But at what levels?