Im currently in the midst of a self build.
As others have said, insulate like crazy, that way it doesn't matter what sort of power you use to heat as youll hardly use any of it anyway.
Wetroom is easy to do at this stage too. A good shed is obviously top priority.
That is the sensible bit, now for the all important frivolous extras 😀
I'm building some proper speakers into the wall of my kitche/family area. 12" subs in huge ported cabinets which will live under a bench and mids and tweeters above, built into solid plywood boxes behind the plasterboard.Add the appropriate crosovers and voila, boomin system for the price of a decent set of floorstanders..
Im using a Myryad MI to power it, built into the wall with the body of it in a cupboard behind for easy cable access and airflow round it.
I'd rather spend on this than a system which plays music throughout the house. Have you ever listened to in wall/ceiling speakers??
My brother in law spent £6000 on one of these systems and now has the pleasure of crappy sound playing down onto his head in every room. He likes it though.
Ive also got a star ceiling kitto use as a nightlight in the upstairs hall/gallery.
Thought about CAT 5 but can't really see what Id ever do with it so didn't bother.
I've seen these shower tv screens. Does anyone really watch TV in the shower?