Good luck to all Run3ers. You will feel amazing afterwards- deservedly so! Like @JustCallMeGriffin I was grinning all day after, because I had amazed myself, and its those days when you realise just how far you've come from W1R1, in surprisingly short a time.
@sleepyhead 8k is absolutely amazing !! Happy playlists are the best. I used to use ELO's Mr Blue Sky at the gym, but that was on a bike, and I think the BPM are a little high for running 5K!
@Cathpot and @StripyHorse I know what you mean about post-programme running. When I repeated W9R3, it was fine, because there was structure, and a defined goal, but running to my own playlist, it's far too easy to think "well, I've run for 20minutes, so I've had a decent workout and I can stop now. Oh, and I need to make DC's lunch and yadda, yadda, yadda" and I just stopped early! 
It's definitely a mental thing. I was fine getting up, dressed, and out, but then on my warmup walk I was sort of thinking "erm, what am I doing?"...and I think I really need to hone a mindset that says- "30mins running- DO IT!" 
My son even said to me on Sunday incredulously "why are you going running? You've finished the programme!" and he was serious.
I can see that having a goal (completing C25K, training for a 10k race etc) is a necessity for me. I need to work on that!