Hunger is very subjective, and regular eating can actually erode your natural hunger/satiety signals - top up frequently and you stop recognising what true hunger really is. Hunger is necessary and useful, and it's harmless - stick with regular meals (three a day works for most people, allowing insulin levels to drop is good for weight loss!) and challenge yourself as to whether you *need* to snack in between.
Running with someone is also very useful, as others have said. Effort is again very subjective, and perceived effort can sometimes be much more/worse than reality. I found having a GPS watch to tell me my pace made a world of difference as it gives you an objective measure of how you're doing. Pacing yourself is key to more sustained running. I'd definitely second going to parkrun - it's such a friendly community, I'm sure you could buddy up with someone (or even just pick someone and tag behind) to help you pace yourself. A run/walk strategy to start with, at a slightly slower pace than is your goal, and you'll find you can cover more ground. Eventually the walking breaks become shorter and the running segments longer, and soon enough you'll be running the whole distance.
Oh, and most people can't run for 5 minutes! A study earlier this year indicated 1 in 5 adults can't run 100m, let alone for 5 minutes. You're probably being a bit hard on yourself
You won't find a lot of races this end of the year (autumn/winter) taking entries for next year if this year's events haven't happened yet! Most don't even release provisional dates until the upcoming event has happened.
Loads of events are taking entries for Jan-August though, and events like Nottingham open entries the day after. Nottingham is a lovely event by the way, I'd definitely recommend it.
All of the events Cake has mentioned above are good 'uns. White Peak sells out very quickly (I was on the website at midnight to get a place!) but is beautiful and lots of downhill. Worksop is a lovely course, but a bit lumpy. Great medal though
The Longhorn is also lovely, and one of my favourite medals. It may be less muddy next year as they've moved the date.
If you're willing to go down in the Midlands a bit, the Shakespeare half is Stratford Upon Avon (unsurprisingly...) and is a lovely event. Due on the 7th May next year, and entries are open http://www.shakespearemarathon.org.uk/
Have you had a look on Fetcheveryone? Their race listings are usually really good, and you might find some smaller events that aren't well publicised.