There's a ton of history there. Try visiting some of the castles, I know Warrick and Arundel are (or at least have been) open to the public, and neither are obscenely far from London, and the Tower of London is also a nice visit if you like that sort of thing. If you go to Southampton, you can visit the HMS Warrior, one of the last surviving Ironclad warships, and right next door in Portsmouth is the even older HMS Victory, Lord Nelson's flagship. Then there's Stonehenge, of course, if you're into the really old stuff.
It goes on and on really, you just gotta look a tiny bit harder as most of it's not in the middle of the city.