The VRR, process seems to be straightforward Ruth, and states "When you are advised that a decision not to bring charges against a suspect or a decision to stop the case has been made, you will be notified, in clear terms, of the right to request a review of that decision. You will be provided with information as to how to exercise the right." (see the CPS link provided).
Please note the time limits that apply for VRR request.
I must point out that the reality is such cases are difficult to meet the required test of evidence required to prosecute (charge) an accused person, however, the details of this individual case and specific reason/s not to prosecute should rightly be fully explained to you at the first consultation. If you are not satisfied with the reasons for the decision then the long overdue VRR is available. Whereas a further review may not succeed in a change of decision, it may help the victim in knowing that they did all they could possibly do to bring the offender to justice.