I think the current layout flows well. You may prefer to have pendant lights above island and above dining table, in which case current positions will work well too.

I'd keep current layout too. I'd think about moving the lantern so it's centred in line with the dining area rather than centred in the whole extension room though. Or put in two smaller rooflights - one above kitchen galley and one between kitchen and living space as those are the areas where you want the light coming in (rather than over half of the sofa or above the TV). What direction does your extension face? I'd also steal some space from the kitchen to make the utility bigger so that it's more useful and easier to use.

Aligning the table position with the the lantern to my mind is the wrong focus. The suggested layout on your plan works very well because it makes the most of the new room features. Bringing the table forward will block your views to the outside whilst you are sat at the sofa because a seated sofa position is a lot lower than being sat at the table. I suspect the idea of aligning the table to the lantern comes from an imagined aesthetic advantage and not from the POV of getting the maximum enjoyment from the space, but trust me when I say it is the latter that’s going to give you the best return on investment because that room will be stunning regardless of where you place the table.
Secondly, from a practical stand point, don’t forget you will need some artificial light to illuminate the table at night. By placing the table under the lantern you will make achieving this technically more difficult and costly. Best of luck with your beautiful new space :)