Here's my prediction.
In the UK, criminal cases start off in either in a magistrates' court or a crown court. Serious cases like rape, murder, and organized crime go straight to the crown court automatically. Minor cases such as driving offences, common assault, or petty theft are heard in the magistrates' court.
Sexual assault is an "either way" offence; it can be tried in either court. That the magistrates didn't send the case to the crown court before the trial means that Griffiths' case isn't particularly serious.
A custodial sentence longer than 6 months is highly unlikely.
He touched her on the arm and waist, while she was clothed, and not on more sensitive parts. The age difference is only 2 years; he's not in a position of responsibility over her. He's young, socially awkward, volunteers, and is a student at a decent university.
I wouldn't be surprised if he walked away with a fine, a community service order, and/or a mental health treatment order. Maybe a suspended sentence.