You could contact the police and tell them you would like the duty solicitor to be available when you attend the police station. This is free.
alternatively you can contact a solicitor yourself to arrange for a meeting ahead of going to the police station. You will not get legal aid.
It perhaps depends on what is going to happen when you attend. If the police intend to interview you about the circumstances, then you may well want legal advice. If the police did not see you driving then they will want to interview you to get an admission that you were the driver. A solicitor might advise that you make a 'no comment interview' as without an admission, there is not enough evidence to prosecute you. You need a solicitors advice for this.
On the other hand, if you were stopped by the police, and it is obvious that you were driving, but for some reason a blood sample was taken at hospital, then you are only going to the police station to be charged with no interview and you do not really need a solicitor for this.