So, after the daftness of double-running Week 8 Run 3b out of sheer joy at at reasonable ambient temperature, I gave the first of the Week 9 30 minute runs a stab.
Went out about 5:30am, pretty clear sky, so the temperature was down to about 7 degrees. I plotted a 15 minutes segment on longest unbroken pavements I could find nearby, looped around, and came back the same way. Nobody else out, don't think I saw a single car.
Legs and lungs felt the cold during the warm-up walk, but settled in after the first five minutes of running. I'd thought about wearing a light running jacket on top of my t-shirt, but by the end of the 30 minutes I was glad I hadn't - I'd accidentally struck just the right balance between workload, clothing and ambient temperature.
My pace steadily increased through the 30 minutes, as I grew in confidence that my lungs weren't about to explode, but I kept it gentle and was careful not to go over the top.
Great run, no problems, no swearing. Looking forward to the next one!