You have to apply for an enforcement order - and pay up front.
If the enforcement is successful you get this money back, but otherwise you lose it.
There are various ways this judgement can be enforced - the court will be very helpful and tell you the options, but will not advise you which one is best in your case.
�80 will probably be best recovered by the bailiff, or if the defendant is working you can get an attachment of earnings. This means the money will be stopped from his wages and his employer will know there is a judgement against him.
There are many other options, but these two are the most relevant, in my opinion.