I SO wish I could see that programme!
Yes, Katla will erupt sooner or later. Your guess is as good as mine about the date. Last ones are 1918, 1860, 1823, 1755, 1721... so you could say she is overdue but then again there have probably been some shallow intrusions (the magma didn't make it to the surface) and they also relieve the pressure in the magma chamber so can delay an eruption.
No, an explosion in the magma chamber is not really an option - apart from anything else you would have to drill down to it place the explosion and even though they draw nice neat shapes of molten magma it is not so simple and there will be a zone of semi-molten mush around it and probably little branches of melt off it. if you drill into one of those then you could get more than you bargained for.
No, it won't be anything like Laki at all. Laki was lots of eruptions along a long fissure and huge volumes of lava. Katla will be pretty much on one site and much smaller in volume but the problem is that Katla is under a glacier and when the hot lava hits the cold water it will explode and that means lots and lots of ash. Sorry about that. No way of telling how big it will be but it could be more ash than the last effort so you had best hope the wind is from the south
Mind you, I am not a vulcanologist so asking me is a bit like asking a foot doctor to do brain surgery
I think we should always expect the unexpected so maybe Askja will give us an eruption, or somewhere near there. I don't mind where, it will be so much fun
