Most training plans I've seen follow the same basic patterns. Beginner plans typically have a long run once a week, increasing (more or less) week over week until 2-3 weeks before the race. 2-3 other runs per week, usually one short one, possibly as some type of speedwork (tempo or interval), then another medium one, somewhere of a moderate intensity, moderate length. Possibly one more run sprinkled in there, maybe a day of cross training.
Plans targeted at advanced users often use the sandwich approach for long runs, where there are two "longish" run days back to back, with a rest day before and after. Some have both the same length, some have one roughly half the distance of the other.
I've found it's really not hard to draft up a training plan on your own; knowing the date of your target event, and working backwards. If you find there's too much time between now and then, repeat a few of the individual weeks as you build up your mileage, or get yourself into a "maintenance" mode once you complete the mileage buildup (be sure to leave about 2-3 weeks to taper, though)
I'm by no means an expert, at all, just suggesting a few things I've found to work well. More than anything else, make sure there's some variety in your training runs, whether that be the mix of speed/slow work, different terrains (hills vs. flat, etc), different scenery, or whatever. Keeping it fun needs to be a top priority... won't much matter how the 30k race goes if you don't (in the big picture) enjoy yourself doing it.
