There are quite a few aren't encrypted (or at least SSL but no authentication needed).
The BBC feeds certainly are open.
There are playlist files out there for UK channels that have worked okay in the past, with BBC, not ITV (but they had STV), Channel 4 (and their other channels). And lots of random other channels, Blaze (I think), shopping channels.
And I have had these working with TVHLink in TV Headend.
The big issue is/was is these go stale really quickly and the one I have been using seems to not be being updated and is mostly broken now.
The only way I see this working in the future would be to have an active project tracking these feeds, a lot of labour.
With the UK government talking about close down of DTT (and DSAT becomes non-viable if Sky pull out as expected in approx 10 years), something will be needed if we have any hope to maintain personal recording on IPTV systems (and TVH systems)