I’m in LOndon too and while they say the ash is no threat, my nasal passages and throat are irritated and I can smell something. It is so weird. We are leaving Monday for Scotland and hope we can get home from there but it is looking very dicey, like we won’t get home for a while. But I love it here, weather is great so it is okay with me.
My DH is in Poland right now and he can smell the volcanic sulphur smell from there.
I am at my Club in London is relative comfort, and very reasonable rate, too. Just a block away from the Hard Rock on Piccadilly, runs £69 a night (with breakfast).
There really is no threat from the ash, other than the smell and possible irritation. I, as a former fighter pilot, have flown through volcanic ash before and no great shakes, it just smells a little like sulfur to me and pits the paint.
Get passengers to sign a waiver for the “health” concern (Asama and such) and let's launch the fleet.