If you could make a pocket door instead of a slider , you could use that entryway space.

Thanks for your comments everyone. We've taken your advice (Luke and NH) and changed the island to a rectangle (1200 x 3000). We lose one breakfast bar seat but gain storage and dining room space plus it shortens the distances from the island to the cooktops. It also removes the need for a corner carousel. We're much happier with this result. Dairy_maid, we've done what you suggested and walked through some common tasks. Overall it works reasonably well although we may keep some coffee spoons and butter knives in the scullery drawers for morning toast and coffee. We've also invested in a "silent" rangehood which has the motor on the outside of the house behind the fridge and we've upgraded the scullery sink to one that is 600 x 400 (internal size). Fabrication starts tomorrow. Woohoo. Once again, thanks so much for taking the time to respond. The design has been significantly improved with your input.

I'm looking for a door lock suitable for a cavity slider that can be locked/unlocked from either side regardless of what the other side is. Sounds confusing???? Let me try and explain, and please see attached photo... we have a cavity slider between our main bathroom and our guest room (Bedroom 4), like a Jack n Jill bathroom or a Poor Man's Ensuite as they're sometimes known by, and I need a lock for it so that if there are guests they can have the door locked from their side but if someone else uses the bathroom it can also locked from that side.

swap your laundry & bathroom spaces and just put a cavity slider from kitchen into laundry and close hallway wall off. much more user friendly, you dont want your laundry in middle of the house!?!