A factory tour by one of the makers could probably be arranged.
As lagopus says above, try and visit the Menin Gate. I had one of the most moving experiences of my life there. I didn't hang around to hear the last post as I was very conscious of the fact that standing under a huge arched monument to over 50,000 soldiers who have no grave, while the bugles sounded would have reduced a grown man who thinks he's tough to tears.
If possible, try and visit a German cemetery too, the vast majority were young men who were fed propaganda, given a gun and told to kill the enemy.
It brings it home what a waste of life the whole horrible episode was.
On a lighter note, when in London, the natural history museum is a must. Even if the exhibits aren't of interest, the building itself is a work of art.
Enjoy your stay in Blighty.