If an offender has been caught and brought before the courts then you can ask to court to make a compensation award against the offender. (That applies to all sorts of crime, such as theft or fraud as well as violent crime). The usual way to do that is through the police.
If you've been the victim of a violent crime you can lodge a claim with the Criminal Injuries Compensation Authority. (That applies irrespective of whether the offender has been convicted or not). You can make the claim directly yourself (
https://www.gov.uk/claim-compensation-criminal-injury ) ; you don't need a solicitor but the charity Victim Support can help you with the process if you feel you need it.