Makes me remember when the Channel Islands switched off. I never did get round to putting on YouTube the cut off that I recorded which I think may still be kicking around on the DVD recorder mainly cause it was just someone pulling the plug nothing nice like the CH4 testcard.
As with when I saw Winter Hill DSO at my parents' house, initially some boxes seem to be putting "inferior" versions of channels on the correct number with the correct/strongest ones in the 80s. This morning on my Humax I had CH23's BBC Mux in the 800s and a version from CH60/61 on 1/2 etc complete with glitching (which I can't work out with a bit of research on Digital UK where they might be coming from - obvious answer for me is Ally Pally but that doesn't seem right). All the other digital tuners (in TVs/DVD recorders) I have seemed to sort it fine.
Nothing that a bit of manual tuning won't sort out for me, but do wonder if some elderly/less techy viewers will have issues with that.