Kingsbridge in the South Hams has a good secondary school and some good primaries (also in the surrounding villages like Thurlstone). Sailing and the coast nearby. No train line though
Brighton is great if you still need to get to London for work. Everything is close by - the South Downs, endless coast, Marina, Sailing clubs in nearby towns. You can get up to Victoria in an hour, tons of restaurants, shopping, theatre etc - aspects of city life but in the Spring, Summer and early Autumn you can come back from work and be up on the Downs or out at sea for a few hours before darkness. Great independent schools and excellent State schools if you pick the right cachement areas. Lots of gorgeous villages just outside Brighton if you want to be feel "more rural" such as Ditchling, Ripe,Poynings.