That's where I got to, although it is difficult information to find and I am still not sure. I think it may come down to legal liability, and although SoL will probably practically provide integrity control for all PBN approaches there is are no longer any legal relationship or obligation on ESA to provide the service and, absent an agreement, continuity of service etc is obviously not guaranteed. My tentative conclusion is that Air Nav Service Providers in the UK should not publish RNP APCH procedures of any sort. I'm finding it very difficult to locate the document that actually says ANSPs have a legal responsibility, though.
This document too