Hello

I have entered a half marathon in september, my training is going well and hope to achieve a time of around 1:45/50.

My main concern is not knowing if I can maintain this pace as my training plan never has me running over anymore than half distance at this pace.

As it is my first race is it just a case of going for it at my pace estimate? I don't want to blow it by heading off too fast

Flakey:d

The only way of knowing if you can keep up this pace is really to bite the bullet and run that distance. An estimate is exactly that, just an estimate, and from experience I've found they can be quite a way off, especially if you're not used to running that far. On top of that, you have to put into the equation things which may affect you during a half marathon which don't at 7 miles such as dehydration, blisters and stamina.

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thanks nick, I suspect I will start at an easier pace and wind it up if feeling good

you need to trust your training plan. If you're training at the right pace, it will bring you to the race in shape to run at your target pace. For the time you mention, you should be doing your long runs at 9 to 10 minutes/mile, tempo runs at about 8 m/mile, and easy runs at about 9.30.
If you run long runs at your proposed race pace, you will be knackered for days afterwards and won't be able to put the effort required for quality sessions. Hance the concept of developing speed, resistance and endurance during separate sessions.

Thanks Greg, that seems to make sense!

Quick tip, write your 1 mile target splits on yuor arm before you start. It'll help you keep a steady pace.