Downloaded the NHS Couch to 5K podcasts last night and went for my inaugral interval run with them. Very bizarre feeling, because to keep to the beat I had to lengthen my strides, which made me feel that I doing that slow-motion run you do when you're on St Andrew's West Sands pretending that you're in Chariots of Fire. But I did notice that sped me up a bit and probably improved my form in using my legs more fully and getting away from 'shuffling'.
I plan to use the speed and stamina podcasts every week and a long run, adding 1k every week to my current distance.
This will mean that I should be running half-marathon distance in 10 weeks' time
And the actual half marathon I plan to do will be in June. So plenty of time if it goes wrong...