Some victims of crime (e.g. assaults) are paid compensation. The victim surcharge (40% of the fine) is used to help fund those payments, and applies to all criminal convictions.
£90 is the guideline prosecution cost for a guilty plea. For a not-guilty plea, it starts about £600.
The Victim Surcharge
does not go to victims of crime. If only it did, as people wait for years to be paid compensation in installments by defendants with no money.
Details of the organisations funded are
here, though the government has yet to publish any accounts showing the total received vs total paid.