Thanks for all your suggestions!
Cake that's funny, your suggestion is very much like what we have at the moment - kitchen diner on the right, sitting rooms on the left, except that the adult sitting room is at the front and the playroom/snug at the back. The trouble with this layout is that the kitchen is in the dark "dungeon" corner, also the kitchen diner is quite long and thin so feels narrow.
It's quite a large house, 5 bed/3 bath and 2500 sq ft so hoping this size room isn't out of proportion? Victorian so high ceilings etc.
RTKanga those doors look great ! not sure about them for the dungeon, (I think I prefer a lower level divider for that, or something more see through like Kallax), but they would be fab for something I want to do upstairs - thanks for the link.
Totally agree about solid + glass bits rather than conservatory.
june your idea is something I suggested to DH - but he is desperate to keep the front room as a more formal room (I call it our shrine to pre DC life) and doesn't want it becoming a playroom - even temporarily and though we hardly use it at the moment... I still think that could be a good solution though so will work on him!
goddess the difficulty is partly that it's a corner so that would mean 2 walls of glass/Crittal and that starts to look a bit office-y to me iyswim? Yes if we had stud walls they would have to have internal windows and/or glass doors to let some light in. Not sure how internal windows would look.
SpottedZebra that's what I'm currently thinking. I also think they'd be more likely to use it if it was an area within the bigger room, rather than a sectioned off room. Once they are older I am thinking a desk/school bag/paperwork/ipad area (all that stuff which otherwise ends up cluttering the hall and kitchen).
user147 I know!! We are reasonably tidy but it's the stuff with nowhere to live that causes the mess... which is why I'm intending to build in shed loads of storage. Laundry will be upstairs. Washing up is mostly done fairly quickly though I do need to think about that. Toys are the big mess issue for us... The layout you're suggesting is kind of what we have now - problem is the kitchen ends up in the dark and narrow space left over. Basically at the moment we are giving the nicest space to toys (and there is not much space for storage in that room for various reasons).
Thanks again everyone! I am still veering towards option 1 with some kind of temporary dividers (Kallax/bookshelves/maybe sliding screens) to section off a play area in the dungeon corner. And big wall cupboards for toy storage in that corner too. Then later to become a sort of home organisation corner. However june's option is still a contender too.