Right, got time to do a more detailed reply.
There's no easy way to say it, getting into live sound is hard. Very hard. It' even harder if you want to earn money doing it.
The first thing to consider is if your son really wants to do live sound (particularly if he's studying film). In many ways it's a really shit job. The hours are horrible, the work is often brutal (think loading 10 tons of gear into a truck in the pouring rain at 3am), the pay when you start out is rubbish (or often non existant) and if you haven't got a thick skin the banter and general fucking about will tear you to bits.
If that hasn't put him off the next thing to consider is getting your foot in the door. Best bet is to go round as many live venues as you can find and work out who books crew for them. Be utterly honest as to your abilities and experience, don't be tempted to bullshit, you won't last more than 5 minutes into your first gig. Be prepared for every venue to say no. However, if you get lucky you might find a venue that needs a spare pair of hands on a gig. This is the chance to learn and ask questions - I always say that there is no such thing a a silly question, but only ever have to ask once.
Oh, don't expect to get paid as a venue employee, every single engineer I know is self employed. You need to register with HMRC. You also need to have public liability insurance.