It will be interesting to see how much ash gets ejected. I remember when the Icelandic volcano erupted in spring 2010 and it shut down Europe's sky for about a month. Imagine that happening again now? It would be an absolute nightmare with all the Christmas travel going on.
Grindavik is only 25km from Keflavik, Iceland's International Airport, so I expect the authorities are watching closely.
Nevertheless, I don't think ash is expected unless/until the lava comes into contact with water, either as sea water or ice, which would generate the explosive activity seen at Eyjafjallajokull.
War does not determine who is right, only who is left - Bertrand Russell
Chichester 12m asl