This week Liz Bonnin is witnessing one of Britain's greatest natural wonders as she takes a trip down the might river Severn during one of its massive tidal bores - and meets the surfers who say there is nothing else like it.Ben Fogel takes his six-year-old son Ludo on a Cornish adventure - where Ludo get the chance to learn to sail and the pair enjoy some rock pooling - all on a stretch of coastline close to Ben's heart.We also return to the Yorkshire Dales and the farm of shepherdess Amanda Owen - where she, husband Clive and their nine children are preparing for the annual country show.