An hour after receiving several nudges in the right direction I ventured out, and it was absolutely fine!
I ditched the podcasts for the first time ever (sorry Laura, I'll be back soon!) and just ran 25 minutes with my own music. I was saving that reward for my first post-graduation run, but I felt I really needed to exorcise my horrible W7R1, so I treated myself to a bit of classic rock and other guilty pleasures. It really helped and I felt much much better today.
Thank you so much to everyone on here for the encouragement!
Now to embarrass number one child by turning up to the school playground looking like a very damp beetroot....