run/walk is the way that the NHS couch to 5k program does it...you just increase the length of the runs and decrease the rests...
I did something similar...unintentionally though..
I picked an arbitrary point that I wanted to get to and went there and back...it happened to be 7.2km..I timed myself and aimed to get faster each outing... The first couple of times I did it I was virtually crippled for days afterwards due to searing pain in my thighs. initially I ran as far as I could and walked a bit then ran etc...eventually I managed to get to a point where I didn't walk but had a slow jog instead to get my breath back....now I can do the distance without to many issues I have moved the distance up to 10km....
I am moving flat next week and to run to the same point and back will be 16km....60% increase on my 10k.....will be challenging and probably not advisable to have such a large jump but I will go back to what I did initially and take a breather when I need it before picking up the pace again...of course all of this will be timed and I will just try and get a few seconds faster the next time out..
I have the 110 and have had it about a month now....its a good bit of kit if you just want to track your run and see your pace/heart rate. Does take about 20 seconds to locate satellites though which can be a pain if it is cold.
Satellite acquisition takes about the same time as my 4 year old garmin 705 bike computer
Paid £79 for mine (with the HR strap) as PCWorld seemed to be clearing them for new stock..
My wife is doing the Edinburgh 10k...we live there....she did the couch to 5k program April/May time and did her first 10k run a week or so before the Edinburgh race for life in which she did the 10k version....she is also signed up to the Half Marathon later this year too.
Good to hear that the food is clean.
I found that keeping a feed diary helped me (initially) to realise what I was actually eating....there were a lot more snacks in my diet than I had realised.