The Driver and Vehicle Standards Agency (DVSA) has the authority to issue fixed penalty notices at roadside checks to drivers who have broken the law. The fixed penalties apply to a range offences, including drivers' hour's law breaches and Driver CPC infringements. It is the enforcement officer's decision whether to offer you a fixed penalty instead of taking the matter to court. Fixed penalties always incur a fine, which can range from £50 to £300 depending on the seriousness of the offence, but may also attract penalty points on your driving licence if the offence is endorsable. 

If, under the totting up process you would potentially go over 12 points, the matter must go to court. You could be fined or disqualified from driving, and DVSA may report the matter to the Traffic Commissioner, who could suspend or revoke your vocational driving licence.

If the offence is endorsable you will have to produce your driving licence at the roadside or within 14 days by post to DVSA. You will have 28 days to decide whether you wish to accept the penalty or to ask to appear in court. It is a legal requirement that the Traffic Commissioner is informed every time you accept a fixed penalty notice as well as when you are convicted.

More information can be found here.