Cannock is a great place to take him, good choice,
only other advice I would add, apart from relax and enjoy
Would be make sure his bike is properly set up if its a new bike, check brakes are set up correctly, tires are at the right TP, quick releases are tight, gears are selecting correctly and bars and stem are tensioned up correctly, plus saddle height.
That way he will not hopefully be fighting against a porly set up bike.
& don’t race off on the first climb & DH, match his pace, enjoy.
Watching a new rider getting the buzz from riding for the first time, is a very special thing to experience, brings back memories for you too, enjoy.