Too bad on The Dark Tower, I highly recommend it if you ever have time, but yes, sort of a Groundhog Day type thing. He's constantly going to his death and because he doesn't learn from it and change things, he keeps realizing just before, sends the note to his younger self to start on the path again...And worst of it, whatever is happening he's doing it to himself with his own actions. He's created his own time loops in a way. I don't know how well it will work, but yeah. Exactly, I don't think that Comic Relief special was a one off. Nothing so far seems to be one off. (like I think the TARDIS is hugely involved in whatever loops is going on.)