It's all about balance, I can run fairly well at 16 kph but it needs concentration and pretty good form. I did a progression run on a treadmaill yesterday 14kph for the first 5k and then cranked it up, 16kph for 1k, 17kph for next 2k, 18kph for 1k and finished last 1k in 19.5kph
Great North Run is now 49 quid, why so expensive when you can book other half marathons for half the price. I've never run the Great North and will be unlikely to do so based on the cost of this race. It is a pretty congested race from what I understand and if I want a race with atmosphere then I'll go for the London Marathon which is pretty much the same price. I'd pay this sort of price tag for a marathon but not for a half!
Praise where praise is due... I too got back into running after losing just over three and a half stone, and started going out with my lurcher for a run once a week but found that this wasn't enough. I joined my local running club more for the discipline that training in a structured way offers. This way you train on certain days/nights and benefit from the experience and knowledge of a qualified coach. Most clubs cater for all abilities, and if you wish to you can enter races and competitions. It is a good way to meet others, socialise and build strength and stamina. Two years ago running a mile was almost unthinkable, my first 10K was in October which I did in a modest 43:30, training has allowed me to knock more than five mins off that time. Structured training is important, as is a good healthy diet, and having clear and pre determined goals. You need to decide whether you wish to be a recreational runner or are interested in stepping up your training and increasing your distance and improving your stamina. Running every day can definitely lead to fatigue and possibly be counter productive. I really enjoy running but understand that overdoing it can lead to being out of the game for a while and would certainly be counter productive. I would recommend joining a club and seeing where you go from there, you can probably try it out for a few weeks to see how you get on, before you make a firm decision.