The maximum penalties (and this is maximum, not probable) for Careless driving is £2500 fine, and between 3-9 points. Dangerous driving is a bit more extreme, the max for dangerous driving (and again this is the Maximum allowed by law) is 2 years in prison, an unlimited fine and an obligatory ban. When you get your licence back after the ban for Dangerous driving, you must sit an extended retest.
Like a say mate theese are the maximum allowed in the courts, and would only be applied to the most extreme cases of each. Again, depending on the circumstances of the situation you may get a small fine and some points, but like a say bud there are so many factors involved. As for your insurance im not totally sure, they would consider it more of a risk than an SP30, however again just depends on the circumstances.
I am really not trying to scare you bud (and hope I am not!!) just giving you the facts