ATVOD are acting way outside of their remit. The Audiovisual Media regulations come from an EU directive which is not about protecting minors but more about ensuring a level playing field between mainstream TV and online "TV like" services.
The UK has gold plated this directive and turned it into a censorship exercise.
ATVOD & OFCOM haven't let a challenge to this go to Judicial Review. In the The Urban Chick Supremacy Cell case, which was backed by some serious legal people (funded by backlash) and on a pathway for Judicial Review, Ofcom overturned ATVODS ruling that the site was an ODPS, thereby avoiding the process which in all likelihood would be a disaster for them.
Initial Response to ATVOD
The new regulations / rules apply to "TV like" services. If you are in the UK and ATVOD label your content TV like and attempt to heard you into their "notified services", I suggest you do not respond and seek immediate legal advice. There are some excellent people out there ready to help and very eager to test ATVODS & OFCOM's remit through Judicial Review.... which of course, ATVOD & OFCOM are equally desperate to avoid.