Mobile Home Permission Advice Needed

[PieFaceShowCase]

DH has lived in a mobile home (cabin-style, not caravan) on his foster father's land for 20 years. The cabin has billed mains electric, a septic tank and shares a water supply with the other properties on the lane. It was never registered with the council, never paid council tax. I moved in for 5 years but we're now renting a house nearby as we've recently had a baby.

We want to return to the site but buy a bigger mobile home; a scandinavian log-cabin type but on an axle so still officially mobile. Do we need planning permission? Do we need to register or something with the council so that we can pay council tax and get school/nursey place for DS and bin collections etc. Would we need to pay back-dated council tax or prove that we'd lived there already?

The possible complicating factor is that DH and his brother are furniture makers and work in a 2 large sheds on the site. The sheds were built 40+ years ago for agricultural use without planning permission (don't think needed in those days). These are not registered for business use either, no business rates paid ( I know, I know). What do they need to do to register them as business use...would they need to pay back dated business rates/ council tax?

Thanks