I know I'm too late with info, but I live near Minehead, and in case you ever come back, or in case anyone else wants to know the same thing, 2 places stand out for me around here. Sparkhayes marsh, between Porlock and Bossington on the coast path, and the geological SSSI of Kleeve beach. (See my photos of it). Sparkhayes was a freshwater marsh separated from the sea by a shingle bank, but a few years ago the sea broke through, turning it into a salt water marsh, which has killed all the trees, leaving them bare and isolated.