You RANG, Sir?
Trim morphs into Captain Spearmint, I'm impressed. I'm also massively impressed with Corleone's times, I can't compete with that.
I do about 20-25 miles a week in training, plus races about every 4-6 weeks (5K, 10K, half-marathons, etc. plus local cross-country league stuff). My 10K PB is a fairly mediocre 43m 22s, but bear in mind I didn't (re-)start running until I turned fifty.
But yeah, the advice here is all good - get decent shoes, don't overdo the buildup - you should increase your speed OR your distance (no more than 10% per week), but not both at the same time. Nick has a point about off-road, but latest research suggests a bit of hard surface impact is actually good for your joints.
Get a copy of Bob Glover's book "The Competitive Runner's Handbook", check out the Runners World UK website. And enter some races.
And the advice I always give in these threads - join your local running club. Good advice, competitive incentive and (if you're lucky) a good social craic.