You'll have it before you go to court, so this part will no doubt be "no evidence" from aoj/cps.
Your mate is a tit, if it's on camera, unless you are VERY lucky and they/he did not do that days calibration check, with another cop driving a car with calibrated speedo towards him or a set distance check etc then you will get done for what the jp/jd sees.
If this were not done it's inadmissible anyway, ask for evidence if necessary under advance disclosure rules.
If you go to a Magistrates court your screwed, as they always side with the police, the magistrates there can decide they have suffecient sentencing power and try you there but you can then enter a "no plea", and have then the option of going to crown court, like on tv but better as there is a jury there and you will get better/fairer/more accurate justice.
The magistrates have no say in the matter of a no plea, and cannot prevent you from taking it to the crown court.
tabetha