You could initiate a private prosecution but it will cost a lot of money. See here:
http://www.yourrights...vate-prosecution.html
When a private prosecution is commenced, the CPS can simply let it take its course or decide to take over the prosecution. If the CPS does so, the Director of Public Prosecutions could then choose to see the prosecution through to a trial, or to simply terminate the prosecution; The relevant CPS policies are here:
http://www.cps.gov.uk...private_prosecutions/
In deciding whether they could have successfully brought a prosecution for 'dangerous driving', the CPS will have had regard to the legal guidance here:
http://www.cps.gov.uk...riving/index.html#a14
You'll see from reading through the 'Charging practice' guidelines that a momentary lapse is usually not enough to sustain such a charge.
The only realistic chance of a prosecution succeeding might have been with a charge of 'careless driving'. The criteria which the CPS will have used are given here:
http://www.cps.gov.uk...riving/index.html#a15
The procedure for making complaints against the CPS can be found here:
23:20 Wed 22nd Sep 2010