Folks;
Firstly, my sincere thanks for the replies and overall information. I am not worthy...
We'll be in the UK / Iceland area, and I'm looking to capture some of the northern sky with a view to making a relatively large (about A2 sized) print or two for the wall on our return. Hence the star tracker. If I'm going to be printing an image that size, I want things to be as sharp as possible.
I have a selection of tripods, aluminium, carbon fibre, and steel. Very conscious of the fact that the more stability the better, but I'm also going to have to carry it hither and yon. And while I still have a reasonable level of fitness, my best days are behind me, so I want to keep it all light.
Hadn't heard of the MoveShoot Move either, will be looking at those as well.
It'll be carrying a load of a Canon 6D with lenses including a Samyang 14mm f2.8, a Canon 35mm f1.4, and possibly a Canon 135mm f2.
Cheers for all the advice folks!