You should attend the nearest Magistrates' Court as soon as possible and explain what has happened. The officers will check to see if a warrant is outstanding and if it is, you may be arrested temporarily whilst you appear before the court, so it is a good idea to go in the morning during the week.
Some warrants are 'backed for bail' which means you will be arrested, taken to the police station and bailed to appear at the next convenient court.
If you fail to attend at court to resolve the matter then you could be arrested and imprisoned.
