I've investigated further and the freehold can be purchased for about 300 notes. Yes permission is required for any improvements etc.
The freehold is owned by a property company (freehold grazer)
They can charge extra for late payments etc.
I will buy the freehold. All the improvements have been done already and it's ready to move into.
Most properties on Alkrington are leasehold apparently and the freehold ones have been bought by the leaseholders.
a 999 year lease is as good as freehold. (Apart from the ground rent and permissions of course)