Staywet,
Rather than make assumptions try taking a look at this
http://redirectingat.com/?id=42X4874...-open-day.html
Depending on how you intend to charge/invoice for these photographs you COULD have the photographer viewed as a crew member rather than a passenger, thus making the flight a commercial trip (for which your son will need more than simply the licence).
The bigger flaw is your assumption that as a basic CPL there will be work/any work options outside of family and friends. Plenty of threads exist, but you'll have to budget for an IR or FI rating too for your son to stand any chance of flying regularly for a 'living'