If you have held your full licence for less than 2 years, then accumulating 6 penalty points will get you banned AND you have to re-sit your test to get a full licence back.
After 2 years then you need 12 points to get banned, but do not normally have to re-sit your test to get your full licence back, although the court can insist on it if they feel it appropriate (maybe you were banned for causing death by dangerous driving, for example).