[BeachBuggyPhil]

Thanks for the replies, excuse the typo in the title, typing to fast!

The larder would probably be a stud wall and built to fit the space with what ever doors work but the wife really wants one so we're having one!!

The large bathroom would be the main bathroom so guests would need access.
Moving the other bathroom to the exterior wall would be good but I'd loose the airing cupboard. I know two doors and double access is more work but I think it'll be cool for two sisters to have that privacy and trust of their own bathroom.

Anyone know about underfoor heating? Can you lay it on a slab without having to use a screed to cover it?