For those who live within driving distance, can I recommend a visit to Fort Nelson on the hills surrounding Portsmouth. Built in the 1860's it is one of the Palmerston Forts and has been turned into a visitor centre with the added attraction of an artillery museum. Its been recently refurbished and is an excellent half day out. There's a lot going on - we went on a wet January morning so the crowds weren't great - and you get a very good idea of what life in one of these forts must have been like. Very cold, probably.
Worth a thought if you ever find yourself in that part of the world for HMS Victory or the RM museum at Eastney.