Sussex Runner, from what I can gather from reading his first post and title, I think he does not wan't to do a half, instead he has experience with 5k but would like to move on to 10k? and only using a treadmill?.
This to me kinda seems like you are shooting yourself in the foot George, 99% of 10k's that you will race will not be on a treadmill.. so when you decide you are fit enough for the 10k you may be in for a shock because running on a treadmill is easier than running in the outdoors.
As suggested before I recoommend finding a 5k to 10k plan and trying to stick with that, is there any reason you do not run outside? or just preference. Running on the treadmill inside in the warm will do you good, but in my opinion there is no substitute for running in harsh conditions to really harden yourself up and prepare you for race day.