Where to fish?

I hope someone can help with my quest!

I have a young son who is bursting to have a go at fishing. He is
particularly keen to eat anything that he might catch, so I thought sea
fishing would be just the job. However I am no angler and have no idea where
I should take him...

I am based in the Reading area, so the obvious venues are either Southsea or
Hayling Island. Are either of these suitable for a young lad with a rod,
reel, spinners and a few feathers? As the rod is quite short, casting miles
from the beach is not an option. What do the panel suggest, bearing in mind
the priority is to have fun (this is a potential hobby so I don't want to
put him off) and perhaps catch nothing more exotic than perhaps a mackerel?

Thanks for any suggestions,

Andy.