The MGDD/A form will only be available to you at the first hearing, as will statements from the police officers. When you are told your results you are only given one reading as the police charge you with the lowest of the 2 readings. If however you are sure that you only provided one specimen of breath at the police station then I would advise that you plead not guilty, the police are required to take 2 specimens of breath at the police station. It is best to write to the police now to request that the CCTV footage from your intoxilyzer procedure is preserved, that way you can request it at the first hearing if pleading not guilty. However, the roadside test is simply a preliminary test and is not evidential, there is no significant procedural error in this not being taken.
I think there may be come confusion as to the calibration of the intoxilyzer. The machine itself upon being turned on does a number of tests to ensure that it is operating correctly. The typical breathlayser printout will look as follows:
Blank 1 000 - This indicates the first check to ensure that there is no alcohol in the machine
Simulator Check 1 035 - This gives itself a reading of 35 of a couple of points either side to check it is reading accurately
Blank 2 000 - Another check to ensure no alcohol is in the machine
Breath Specimen 1 066 - The first specimen provided
Blank 3 000 - Another check to ensure no alcohol is in the machine
Breath Specimen 2 066 - The second specimen provided
Blank 4 000 - Another check to ensure no alcohol is in the machine
Simulator Check 2 035 - The final check to ensure that the machine is reading accurately
As you can see from the above, the machine does a number of checks and self-calibrates before each use. If you are looking to challenge the allegation on a technical basis it is normally a good idea to have a specialist representing you. If this is something that you are interested in you are welcome to contact my department on 0333 999 7158.