There is no longer an optional blood or urine sample.
Previously if your breath reading was over the limit but below 50 you had the chance to give a blood or urine sample. The theory being that this would be more accurate than the breath reading.
This changed in April 2015 and you no longer have the option you will just be charged. Of course if your reading is very close to the limit you have the option of challenging the machine if you believe that it was faulty.
Call us for free initial advice and an honest assessment of your case on 01623 397200