I went to court last year for the exatct same offence and won. I would seriously advise a solicitior if you can mate. I represented myself but it was a very daunting experience,and they tried to rip me apart anyway they could.
The statements from the officer that supposedly saw me (PCSO) and the officer that actually nicked me (traffic) didnt correspond with each other and because i didnt have a solicitor the court clerk acted on my behalf. there was so many inconsistencies that the PCSO even admitted that he may have got it wrong and that I wasnt on the phone.

the most you will get is 3 points. But you will also get a fine plus court costs if you lose.

If you do decide to represent yourself make sure you make plenty of notes and thouroughly read the statements for anything that may help you.