If he is still living at the premises or you know where he has moved to, go to your local county court and pick up some papers for the small claims court.
You can fill these in yourself ( honestly ) or get the CAB or someone with some legal experience to do this.
Then go back to the court and pay the fees ( less than £100 ) and the court will issue him with a court order.
You can then proceed with the case ( represent yourself ) and if he does not turn up it will be awarded in your favour. If he does turn up and loses the case, then the court will order him to pay costs ... if he doesn't pay up, the court will remind him.
This will also be on record, so if any searches are made then they will be found .... this also applies to the EU.
Goodluck ..... I took someone to court from Denmark and forced them to return to the UK .... you'd be surprised.