Recently involved in RTI, blew a 41 roadside and taken to hospital to be checked over.
I waited 3.5 hours at the hospital for the blood sample to be taken & opted to keep one of the samples for independent analysis.
Solicitor advised it could be up to 6months waiting on the blood result from the police.
After calling round I found a UKAS accredited company who turned it around in 8 days for me and cost me £180.
Blood alcohol result returned was 74mg/100ml. Limit is 80mg level ± 1mg/100ml.
Have been advise to submit this to the police as it may save them time / money having my sample analysed. Regarding back calculations I have read a few people having that done. I think this depends on the individual incident as the cost involved is high and a lot of variables such as food consumed, age, weight, height you would also be required to be interviewed detailing the 24hours prior - assuming this may be difficult to remember and “no comment”