We have a ceiling mounted extractor in a very large room and it works really well. We ended up with a Brittania BEST extractor (bought from John Lewis) simply because we have a structural steel running above and the position of the internal ducting fit best with that model, though it's a bit bigger than we ideally wanted. The slightly lowered section of ceiling around the extractor is also because of the steel and wouldn't otherwise have been needed. We were actually told that there is a minimum height, rather than maximum, for it to work properly - see http://www.besthoods.co.uk/2011/08/ceiling-extractors-8-things-you-need-to-consider-before-buying-a-ceiling-hood/ It's very powerful and we've had no issues with it. A family member has the pop up option and that has been a bit of a hassle - it's not that powerful and ends up getting dirty from cooking every time.

You can just put Ikea drawer cabinets back to back. Ikea carcasses are very high quality. Look here http://www.ikea.com/gb/en/ideas/3-ways-to-think-about-your-kitchen-1364308671815/?N=0+4294966694&Nr=content.type%3Ai%3Aideas&Ns=rank%7C0&t=ideas&filter=Kitchen. Our webshop provides fronts, side panels and even worktops to customise it www.customfronts.co.uk :-)

I'm not being creative enough I think. Was hoping to have a little island in the middle of room but not sure I can get cupboards in towards sloping ceiling and have the island too. Floor to ceiling cupboards for higher section

I think the kitchen design should be tweaked. Consider moving the ovens near the hob for both easy of use and safety. Since the island is not symmetrical because the seating is to one side, consider moving the hob in line with the two tall cabinets behind the island (which is where I think you should have your ovens). This will look logical and makes your food prep space bigger. The room looks large enough for a better island, consider if you can go deeper for better seating space at the end. Consider going longer to fully use the space at the stool end. And since you asked about light I think you need task lighting over the hob. A long linear pendant works with this style of kitchen. Alternatively choose glass light shades and lie them up in uneven numbers. The number depends on size of pendant but you need a minimum of three and five looks great.