The UK TCM has for a long time been a pale imitation of the US version. The range of films shown is pretty limited, usually being 70s or later. There are few B&W films, and some years back they stopped broadcasting in HD altogether. So the picture quality is just awful.
I've never known it to have intros, or even seasons of films. And I'm also pretty certain it does show films with ads.
To be honest, for archive films Talking Pictures TV is far better, although unfortunately they too are SD only and are entirely ad funded. TPTV is a fascinating story because they're completely independent and have just a small handful of employees, almost run from a garden shed. They do some intros and show obscure little British films and shorts that would never get shown anywhere else. They also dig deep into British archive TV. Film4 is also better than TCM although they skew more modern and cult than older, and they no longer do the intros that they used to.
There is no Criterion Channel in the UK sadly, although the BFI has a decent streaming service.
Adam