Making off without payment (known as �bilking�) is contrary to the Theft Act 1978. It is an �either way� offence, meaning it can be dealt with at either the magistrates� court or the Crown Court.
Sentencing guidelines vary enormously and magistrates� sentencing guidelines suggest a starting point of a fine or a dsicharge for a first time offender pleading Not Guilty.
Your friend�s guilty plea will go in his favour, but the offence is considerably aggravated by the relatively large amount involved and the fact that it was committed on a number of occasions, giving it a �planned and organised� element.
Magistrates have the power to commit the matter to Crown Court for sentencing and would normally do so if the total involved exceeds �5,000. Your friend should have been given an indication of the Bench�s intentions following his guilty plea.
If the magistrates do retain jurisdiction I imagine his guilty plea will keep him out of prison and he will be looking at a hefty community penalty, prboably involving unpaid work of around 200 hours.