Don't forget that councils are now under a duty to host a register of interest in self and custom build. 

The Self-build and Custom Housebuilding (Register) Regulations 2016

Officials have already done a desktop survey of compliance - you can expect another one with potential sanctions soon. There are still a small number of councils who have not got a register at all, and many more who have chosen to bury it in a dusty corner of their website.