Another PVR solution that has UK users suffering from the outage of the XMLTV Radio Times grabber is GB-PVR (from New Zealand).
A user posted a query which I replied to - and as a result I had a look at the database tables that it uses for scheduling recording. Didn't look very hard to add new entries into it ... so added in the basics.
Have hard-coded a few things for now - but fundamentally it looks right.
As always - now need some users to give some feedback to see if what I have done really works in their configuration.
Have also posted a note in the GB-PVR forums - just in case the developer is not happy with such an approach (for example - there could be cleaner and more supportable ways to do it.)