I was exactly the same. In my opinion, a half marathon is definitely a trainable in under a year. If you are really motivated to start early and go steadily.
I started training in June-an 8 week Couch to 5K program, then gradually built up my weekend run until I did my 10k race (that I chose to submit for a qualifying time) in October, then kept on, usually with 3 runs a week, and was ready in plenty of time. I used a ZombiesRun! Couch to 5K plan/app- which I liked because the early weeks I was instructed to "slowly run for 15 seconds", then walk for 1 minute (plus entertainment and someone in my ear coaching me along). I can handle that!
I started the Couch to 5k before registration (which used to be in July)- just to see if I liked it before committing. I wanted to know I would enjoy the training process- since I would spend way more time training than actually at WDW.
IMO the key is to go s l o w l y. I think there are some issues all new runners get as you start developing- like calf pain and shin splints- and I had built in enough time in my plan that I could baby the heck out of myself when they popped up. I built plenty of rest days into my training plan (I ran Sun, Tue, Thurs usually, and towards the end I might add in an interval run. ZombiesRun actually has Half Training plans now but I don't like them because they want 5 days of running/week and that doesn't fit with me at all. Their Couch to 5K, on the other hand, is 3 sessions a week and they tell you at the end of each one to rest up and come back "the day after tomorrow").
If I needed it, I would skip a days run rather than run with pain.(I'd seen a youtube video about a woman who had been training for her first Princess Half and ended up getting a stress fracture and not being able to run- and I confess it made me a little paranoid, but in hindsight, the paranoia kept me pretty healthy!)
And- although this is not for everyone- I did a training plan that included long runs that went up to 14 miles. Most 12 week plans will top out at 10- by then you have built the lung and leg capacity you need and that plus the adrenaline of the race is supposed to carry you the last 3 miles. But I am of a distrustful nature and I needed to know before race day that not only could I do this, I could do it and have some left in the tank, so I went to 14. (As it turns out, with all the weaving in and out- according to my running app I actually ran 13.8 miles on race day so this came in handy!)