If a driving offence takes you to 12 (or more) penalty points, the matter can't be dealt with by the same people that deal with fixed penalties. You will be summoned to appear before a court, so that the magistrates can decide what to do.
The court is obliged to ban you from driving unless you can show that there are 'exceptional circumstances'. Magistrates are instructed that such circumstances must be really exceptional to prevent them from imposing a driving ban. In particular, they're told that the fact that an offender will lose their job if they're banned does not count as 'exceptional circumstances'.
If you can show, for example, that your seriously ill child would be unable to attend vital hospital appointments if you were banned, you might well stand a reasonable chance of keeping your licence. Otherwise a ban is effectively automatic.
Chris