I've just booked for this guided walk myself, and agreed to give it some publicity, as there are still places available.
Though the theme is historical, Church Norton is right beside Pagham Harbour, so there will certainly be birdwatching opportunities before and after.
You can book by phone with Pagham Harbour visitor centre on 01243 641508 between 10 am and 4 pm
St Wilfrid's Chapel