Cheers for the nod Norman.
3 points for an SP30 generally won't make a difference unless you have disclosed previous points and/or claims, in which case it could cause a very large hike.
Also, you have to factor in your age, occupation, car type, etc - lot of factors go into calculating your premium.
Worst case scenario if this is all you have should be an additional premium to pay - normally around the �40 odd mark.
But Norman is right - I've seen some policies cancelled for an SP30 (very, very rare), but it's computer software that calculates the premium, and if the SP30 causes your premium to jump by an extra 50%, then you could possibly see this happen.