Dont forget there's also the Historic Dockyard at Chatham
HMS Gannet a Victorian Sloop
HMS Cavalier a WWII Destroyer which also sits in the drydock where HMS Victory was built
and HMS Ocelot an O class sub from 1962
Paddle steamer trips on the Kingswear Castle along the River Medway to Rochester where you can then visit the castle or wander around the city and visit the Charles Dickens museum
An hours drive from London
http://www.thedockyard.co.uk/Netsite..._Warships.html
From Chatham you can drive down to the RAF Museum at Manston, or go direct to the White Cliffs experience at Dover.
I recon your going to need at least a week