If you are very keen in knowing UK's history, take a walk around Windsor Castle and you will know everything about the monarchy. I am saying this is because I had personal experience and the level of information which you will receive is magnificient.
No doubt that you can't take any pictures when you are actually inside the State Department building within the Windsor Castle, nevertheless, the experience was exciting. Words can't fully express how much joy was I when I had the opportunity to pay a visit to Windsor Castle. Guys, if you have the opportunity, please get yourselves over there, alright? The scenery is beautiful and you will be absolutely godsmacked.
Besides the State Department, you will be advised of the fire which occured back in 1992 and the Doll House. You will also be given information to Henry VIII's famous paintings of himself and his children. It is a golden chance which you should not miss.