Out of the forest and down to the sea, you can’t go far wrong with any of the beaches along the coastline but here are my favourites:
Avon Beach: http://www.avon-beach.co.uk/
Lepe Country Park: https://www.hants.gov.uk/thingstodo/countryparks/lepe
Christchurch Quay: https://www.visit-dorset.com/things-to-do/christchurch-quay-p1152973