My take on nutrition for a half marathon is first as how long will it take for you to run it? The widely accepted time for running without taking on extra fuel is 90 minutes. This is OK for faster club runners but not if you are going to be out there for over 2 hours. Not suggesting gels every half hour or such just an odd one at 90 minutes to get you home.
Just did my first full at York in 5 53 slow to some but great for me as best half 2 38 but it is training and having confidence that training will pull you through. Passed a few in last 6 mile that gave me a mental boost.
Talked to a guy struggling at about 19 mile "only done a 10k before". Thought he could multiply his 10 by 4 and finish full in under 5 hours.