I'd put another set of sliding doors between the lounge and the playroom rather than a solid wall. Reason being is that it gives you more options. You get to sequester the mess and noise when you want and you still get a good flow later on when the kidlets aren't such mess monsters. I'd make both sets of sliding doors have full-length frosted glass inserts. That will let in the light. Or you could use shoji doors if that suits the decor better. From your plan, I'm assuming the house is semi-detached, so windows on the right wall aren't possible? Also, you might consider a pocket door from the hallway to the lounge and from the hallway to the utility room. That way you don't have to allow space for door swing.

Post with pictures on design dilemma.

Glass splashbacks are a great idea , glass is so easy to keep ! there is such an extensive range of colours available ! It finishes off a kitchen so nicely tiles are great too but there's an awful lot of upkeep involved !

Attached are drawings and an image of our new kitchen - I am struggling with best place for sink - our hob is on the back wall rather than the island - so currently island is just seating and storage. Also will include some colours I was thinking of using for cabinets - we are thinking island the darker colour with wall cabinets the brighter colour. All advice or thoughts welcome!